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Author SHA1 Message Date
kennethreitz 691f6b4d5c Bump version to 3.6.0 and update changelog
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-24 16:24:03 -04:00
kennethreitz 90a082a0ac Add structured logging with per-request context (#604)
## Summary

New `enable_logging=True` parameter on `responder.API()` that provides
structured, request-scoped logging using stdlib `logging` and
`contextvars`.

### What it does

- **`api.log`** — always available on every API instance. Works as a
plain logger by default; gains per-request context enrichment with
`enable_logging=True`
- **Per-request context** — every log message automatically includes
request ID, HTTP method, path, and client IP
- **Access logging** — logs every request with timing: `GET /path → 200
(1.2ms)`
- **Request ID** — generates or forwards `X-Request-ID` headers
(supersedes `request_id=True` when both are set)
- **stdlib logging** — works with any existing handler, formatter, or
log aggregator

### Usage

```python
# api.log always works — no setup required
api = responder.API()
api.log.info("starting up")  # plain logger, no context

# With enable_logging=True, log messages get request context automatically
api = responder.API(enable_logging=True)

@api.route("/")
def index(req, resp):
    api.log.info("handling request")
    # => 2026-03-24 12:00:00 [INFO] responder.app — handling request [GET /] [req:abc123] [client:127.0.0.1]
```

For additional loggers in helper modules:

```python
from responder.ext.logging import get_logger
logger = get_logger("myapp.db")
```

### Architecture

- `responder/ext/logging.py` — self-contained module with:
- `LoggingMiddleware` — pure ASGI middleware that sets contextvars and
logs access
- `RequestContextFilter` — logging filter that injects context into
records
  - `RequestContext` — read-only access to current request metadata
  - `get_logger()` / `setup_logging()` — convenience functions
- `api.log` — always a valid logger; context-aware when
`enable_logging=True`, plain stdlib logger otherwise
- Wired into `API.__init__` via the `enable_logging` parameter

### Files

- `responder/ext/logging.py` — new module
- `responder/api.py` — added `enable_logging` parameter and `api.log`
- `tests/test_logging.py` — 9 tests
- `docs/source/tour.rst` — new Structured Logging section
- `docs/source/index.rst` — added to feature list

## Test plan
- [x] 9 logging tests pass
- [x] Full suite: 208 passed

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-24 16:22:57 -04:00
kennethreitz 5ee0de6458 Replace HTTP/2 server push with dependency injection in backlog
HTTP/2 server push was removed from the spec and dropped by browsers.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-24 16:02:56 -04:00
kennethreitz 1c729c8542 Docs: second improvement pass (#603)
## Summary

- **Auth tutorial**: fix deprecated `datetime.utcnow()` →
`datetime.now(timezone.utc)`, add role-based access control section, add
auth strategy comparison guide
- **WebSocket tutorial**: use `WebSocketDisconnect` instead of bare
`Exception` in chat example, add connection lifecycle section with close
codes, add rejected connection test example
- **SQLAlchemy tutorial**: modernize from `Column()` to
`mapped_column()` / `Mapped[]` (SQLAlchemy 2.0 style with type checker
support)
- **Deployment**: use `uv` in Docker example instead of pip, fix stale
`uv.lock` reference in production checklist
- **Quickstart**: link to all tutorials in "next steps" (was only
linking to 3 of 9)
- **Sandbox**: rewrite with project layout tree, mypy command, and
pattern-matching test examples

## Test plan
- [x] `make html` builds cleanly
- [x] All 199 tests pass

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-24 16:00:56 -04:00
kennethreitz 536428a787 Remove Unreleased section from changelog
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-24 15:54:13 -04:00
kennethreitz 3d5f3c7e93 Improve documentation across the board (#602)
## Summary

- **Deployment guide**: health check endpoint, Docker Compose example,
Caddy reverse proxy config, Procfile pattern, production checklist
- **API reference**: quick usage examples for every class (API, Request,
Response, RouteGroup, BackgroundQueue, RateLimiter, status helpers)
- **Feature tour**: new Pydantic validation and content negotiation
sections, expanded MessagePack docs
- **Testing guide**: rate limiting and mounted WSGI app test examples,
Werkzeug 3.1.7 tip
- **Middleware tutorial**: pure ASGI middleware example (no
BaseHTTPMiddleware dependency)
- **CLI guide**: environment variables section (PORT, SECRET_KEY)
- **Homepage**: updated feature list with SSE, rate limiting, Pydantic,
content negotiation, route groups
- **Backlog**: removed already-implemented items, added current ideas

+362 lines of docs, no code changes.

## Test plan
- [x] `make html` builds cleanly with no warnings
- [x] All 199 tests pass

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Signed-off-by: Kenneth Reitz <me@kennethreitz.org>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Co-authored-by: Andreas Motl <andreas.motl@panodata.org>
2026-03-24 15:51:55 -04:00
kennethreitz e0cce231ea Update CLAUDE.md to reflect lock file status
Signed-off-by: Kenneth Reitz <me@kennethreitz.org>
2026-03-24 15:42:14 -04:00
Andreas Motl 44c33475b2 Remove dependency lock file uv.lock. This is a library. (#601)
## About
We think using an `uv.lock` file is only applicable for applications,
and otherwise gives wrong impressions and expectations.

## References
- https://discuss.python.org/t/the-purpose-of-a-lock-file/38756
- https://github.com/orgs/python-poetry/discussions/7847
2026-03-24 15:35:41 -04:00
kennethreitz f4a292108b Move version below tagline in docs sidebar
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-24 15:34:49 -04:00
kennethreitz 25ea333ad4 Prefix version with v in docs sidebar
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-24 15:33:12 -04:00
kennethreitz 6279835040 Show version number in docs sidebar
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-24 15:32:48 -04:00
kennethreitz 0e493ad8d1 Add CLAUDE.md and /release command
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-24 15:31:42 -04:00
kennethreitz ce3ab46d59 Bump version to 3.5.0 and update changelog
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-24 15:27:36 -04:00
kennethreitz 6f9c87d71c Fix broad exception handling and future.result() call
- Call future.result() instead of bare property access in test (#596)
- Catch (ValueError, TypeError) instead of broad Exception in
  response model serialization (#597)
- Catch WebSocketDisconnect instead of broad Exception in
  websocket chat example (#598)

Closes #596, closes #597, closes #598

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-24 15:25:12 -04:00
kennethreitz 29d0621d98 Replace deprecated asyncio.iscoroutinefunction with inspect.iscoroutinefunction
Closes #599

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-24 15:23:24 -04:00
kennethreitz 30fa2dfda7 Add uv.lock
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-24 15:22:06 -04:00
kennethreitz 43c803a426 Restore print statements in lifespan example
These serve as illustrative markers for users reading the example.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-24 15:21:21 -04:00
Andreas Motl ff6d530338 Chore: Code formatting (#594)
## About
A few cosmetic adjustments aka. code formatting.
Also validate the outcome on CI/GHA.
Feel free to improve now or later at your disposal.

## Details
The updates are based on using the most recent versions of pyproject-fmt
and ruff.
Specifically, spots marked with `noqa` might need further love, also at
your disposal.

---------

Co-authored-by: Kenneth Reitz <me@kennethreitz.org>
2026-03-24 15:21:04 -04:00
kennethreitz a375984310 Fix WSGI mount returning 400 at mount root (#600)
## Summary
- When a WSGI app (e.g. Flask) is mounted at `/prefix` and a request
hits exactly `/prefix`, the path prefix was stripped to `""` instead of
`"/"`, causing frameworks like Flask to return 400.
- One-character fix: default the stripped path to `"/"` when empty.

## Test plan
- [x] `tests/test_responder.py::test_mount_wsgi_app` now passes

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-24 15:16:29 -04:00
Andreas Motl 46c6f440c5 Chore: Remove configuration for Read the Docs (#595)
https://responder.kennethreitz.org/ is here to stay.
This patch concludes the decision in GH-564.
2026-03-23 20:19:15 -04:00
Andreas Motl c87e8c876d CI: Validate on Python 3.14 vanilla, free-threaded, and PyPy (#593) 2026-03-23 18:28:27 -04:00
kennethreitz f86c7eed70 Fix RST title underline warning breaking docs CI
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-22 22:10:51 -04:00
kennethreitz 9d492a383c Add marimo notebook mounting docs and example
- Document mounting marimo ASGI apps in the feature tour
- Add examples/marimo_mount.py showing the integration
- Verified working: marimo.create_asgi_app() mounts cleanly via api.mount()

Fixes #580.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-22 22:09:01 -04:00
kennethreitz 77ae49aaef Improve GraphQL API interface, expand tests, drop 3.9 from CI
- Extract variables and operationName from query params and form data,
  not just JSON bodies. Fixes #571.
- Add docstrings to GraphQLView class and methods. Fixes #572.
- Add 10 new GraphQL tests: variables, operationName, mutations,
  context access, malformed queries, raw text, invalid variables
  param. Fixes #568.
- Remove Python 3.9 from CI matrix (dropped in 3.4.0).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-22 22:06:00 -04:00
kennethreitz 74c872ed57 Add type annotations to routes.py
Add comprehensive type hints to compile_path, BaseRoute, Route,
WebSocketRoute, and Router classes. Uses Starlette's Scope, Receive,
Send types and properly types the ASGI/WSGI union in Router.apps.
Fixes #566.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-22 21:47:21 -04:00
kennethreitz 724b769c9e Fix OpenAPI template packaging, add static file tests
- Include ext/openapi/docs/*.html in package_data so OpenAPI docs
  themes (swagger_ui, redoc, rapidoc, elements) ship with the wheel.
  Fixes #583.
- Add tests for static file serving and index.html fallback. Fixes #563.
- Bump version to 3.4.1.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-22 21:44:02 -04:00
kennethreitz 4f02016ed6 Add comprehensive docstrings, expand API reference, upgrade to Starlette 1.0
- Add docstrings to all undocumented public methods across API, Request,
  Response, Router, Route, BackgroundQueue, and related classes
- Expand api.rst with autodoc sections for RouteGroup, BackgroundQueue,
  QueryDict, and RateLimiter
- Update starlette dependency to >=1.0
- Drop Python 3.9 support (required by Starlette 1.0), minimum is now 3.10
- Bump version to 3.4.0

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-22 21:37:36 -04:00
kennethreitz 3c2b1acc19 Bump version to 3.3.0 2026-03-22 13:58:18 -04:00
kennethreitz a3b49ab9fd Add auth, WebSocket, middleware, config guides. Examples and changelog.
New documentation pages:
- Authentication: API keys, JWT tokens, session auth, custom exceptions
- WebSocket Tutorial: echo server, chat room, HTML client, data formats
- Writing Middleware: hooks vs middleware, Starlette integration, ordering
- Configuration: env vars, .env files, secret keys, debug mode, production setup

Also:
- Complete working example at end of quickstart with cross-references
- Three new example files: rest_api.py, websocket_chat.py, sse_stream.py
- Changelog updated for v3.2.0

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-22 13:56:35 -04:00
kennethreitz bf17b02653 Add tutorials: REST API, SQLAlchemy, Flask migration. Rewrite CLI and API ref.
Three new tutorial pages:
- Building a REST API: full CRUD with Pydantic validation, from scratch
- Using SQLAlchemy: async engine, lifespan setup, CRUD with ORM
- Migrating from Flask: concept mapping, quick reference table,
  gradual migration via app mounting

Also rewritten:
- CLI docs: cleaner, more concise
- API reference: added prose descriptions for each section

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-22 13:34:01 -04:00
kennethreitz 9383cd0f16 Rework homepage prose for better flow
Lead with recognition, earn each paragraph, land on the welcome.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-22 13:09:46 -04:00
kennethreitz 226bd63ed3 Full docs pass: educational prose throughout all pages
Every section now teaches web development concepts alongside the code:
- HTTP methods, status codes, content negotiation explained
- What ASGI is and why it matters
- How cookies, sessions, CORS, and HSTS work
- When to use WebSockets vs SSE
- Why request validation matters
- How background tasks differ from task queues
- What rate limiting protects against
- What Host header injection is
- Separation of concerns in templating

People should learn about web development while reading these docs.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-22 13:07:56 -04:00
kennethreitz b3c55f68d9 Expand testing docs with prose, examples, and tips
New sections: request validation, headers/cookies, custom error
handlers, before/after hooks, and practical tips. Every section
now explains the why, not just the how.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-22 13:00:29 -04:00
kennethreitz a2a2ae21ff Good intentions
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-22 12:58:05 -04:00
kennethreitz 84074860aa Add note about Responder's spirit as a passion project
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-22 12:55:36 -04:00
kennethreitz 21baa03640 CI: Add CNAME for custom domain in GitHub Pages deploy
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-22 12:51:14 -04:00
kennethreitz 0c552e25cb CI: Deploy docs to GitHub Pages on push to main
Uses peaceiris/actions-gh-pages to push built docs to gh-pages branch.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-22 12:48:05 -04:00
44 changed files with 4193 additions and 719 deletions
+42
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@@ -0,0 +1,42 @@
Release a new version of responder to PyPI and GitHub.
Usage: /release <version> (e.g. /release 3.6.0)
If no version is provided, ask the user what version to release.
## Steps
1. **Verify clean state**: Run `git status` and ensure the working tree is clean. If not, stop and ask the user.
2. **Run tests**: Run `uv run pytest -x --no-header -q`. If any fail, stop and report.
3. **Bump version**: Update `responder/__version__.py` to the new version.
4. **Update changelog**:
- Run `git log --oneline $(git describe --tags --abbrev=0)..HEAD` to get commits since last release.
- Add a new section in `CHANGELOG.md` under `## [Unreleased]` with the date, categorized into Added/Changed/Fixed/Removed.
- Update the compare links at the bottom of the file.
5. **Lock deps**: Run `uv lock`.
6. **Commit**: Stage `responder/__version__.py`, `CHANGELOG.md`, and `uv.lock`. Commit with message `Bump version to X.Y.Z and update changelog`.
7. **Push and tag**:
```
git push
git tag vX.Y.Z
git push origin vX.Y.Z
```
8. **GitHub release**: Create a release with `gh release create` including highlights and a link to the full changelog.
9. **Build and publish**:
```
uv build
uvx twine upload dist/responder-X.Y.Z*
```
Note: This requires a PyPI token. If twine fails due to auth, tell the user to set `TWINE_USERNAME=__token__` and `TWINE_PASSWORD` and re-run, or run `! uvx twine upload dist/responder-X.Y.Z*` interactively.
10. **Update GitHub release**: Edit the release to add a link to the PyPI page: `https://pypi.org/project/responder/X.Y.Z/`
11. **Report**: Print a summary with links to the GitHub release and PyPI page.
+11
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@@ -11,6 +11,9 @@ concurrency:
group: ${{ github.workflow }}-${{ github.ref }}
cancel-in-progress: true
permissions:
contents: write
jobs:
documentation:
@@ -40,3 +43,11 @@ jobs:
- name: Build static HTML documentation
run: sphinx-build -W --keep-going docs/source docs/build
- name: Deploy to GitHub Pages
if: github.ref == 'refs/heads/main' && github.event_name == 'push'
uses: peaceiris/actions-gh-pages@v4
with:
github_token: ${{ secrets.GITHUB_TOKEN }}
publish_dir: ./docs/build
cname: responder.kennethreitz.org
+3 -1
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@@ -20,11 +20,13 @@ jobs:
fail-fast: false
matrix:
python-version: [
"3.9",
"3.10",
"3.11",
"3.12",
"3.13",
"3.14",
"3.14t",
"pypy3.11",
]
env:
UV_SYSTEM_PYTHON: true
+1
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@@ -8,6 +8,7 @@
.DS_Store
coverage.xml
.coverage*
*.lock
__pycache__
tests/__pycache__
-33
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@@ -1,33 +0,0 @@
# .readthedocs.yml
# Read the Docs configuration file
# Details
# - https://docs.readthedocs.io/en/stable/config-file/v2.html
# Required
version: 2
build:
os: "ubuntu-24.04"
tools:
python: "3.12"
python:
install:
- method: pip
path: .
extra_requirements:
- docs
sphinx:
configuration: docs/source/conf.py
# Use standard HTML builder.
builder: html
# Fail on all warnings to avoid broken references.
fail_on_warning: true
# Optionally build your docs in additional formats such as PDF
#formats:
# - pdf
+124 -2
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@@ -5,7 +5,125 @@ All notable changes to this project will be documented in this file.
The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/), and
this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
## [Unreleased]
## [v3.6.0] - 2026-03-24
### Added
- Built-in structured logging with per-request context (`enable_logging=True`)
- `api.log` — always-available logger, enriched with request context when logging is enabled
- Automatic access logging with timing: `GET /path → 200 (1.2ms)`
- Request ID generation/forwarding via `X-Request-ID` header
- `contextvars`-based request context (ID, method, path, client IP) on every log record
- `responder.ext.logging` module: `get_logger()`, `RequestContext`, `RequestContextFilter`
- CLAUDE.md project guide and `/release` command
- Version number in docs sidebar
### Changed
- Comprehensive documentation improvements across all pages
- Deployment: health checks, Docker Compose, Caddy, Procfile, production checklist
- API reference: usage examples for every class
- Feature tour: Pydantic validation, content negotiation, structured logging sections
- Tutorials: modernized SQLAlchemy to `mapped_column()`, fixed deprecated `datetime.utcnow()`,
WebSocket `WebSocketDisconnect` handling, role-based auth, auth strategy guide
- Testing: rate limiting and WSGI mount examples
- Middleware: pure ASGI middleware example
- Quickstart: links to all tutorials
- Sandbox: full rewrite with project layout
- Docker example uses `uv` instead of pip
- Backlog updated: removed implemented features, replaced HTTP/2 server push with dependency injection
### Removed
- `uv.lock` — this is a library, not an application
## [v3.5.0] - 2026-03-24
### Added
- CI validation for Python 3.14, 3.14 free-threaded, and PyPy 3.11
- Marimo notebook mounting docs and example
- Type annotations for `routes.py`
### Changed
- Replaced deprecated `asyncio.iscoroutinefunction` with `inspect.iscoroutinefunction` ahead of Python 3.16 removal
- Narrowed broad `except Exception` to specific exceptions in response model serialization and websocket chat example
- Improved GraphQL API interface with expanded test coverage
- Code formatting cleanup via pyproject-fmt and ruff
- Dropped Python 3.9 from CI
### Fixed
- WSGI mount returning 400 when requesting the exact mount root path
- Werkzeug 3.1.7 compatibility for trusted host validation in tests
- `future.result` bare property access in background task test (now properly calls `future.result()`)
- OpenAPI template packaging and static file serving
- RST title underline warning breaking docs CI
### Removed
- Read the Docs configuration (docs hosted on GitHub Pages)
## [v3.4.0] - 2026-03-22
### Changed
- Upgraded to Starlette 1.0
- Added comprehensive docstrings across the codebase
- Expanded API reference documentation
## [v3.3.0] - 2026-03-22
### Added
- Full documentation rewrite: tutorials for REST APIs, SQLAlchemy, Flask migration
- Auth, WebSocket, middleware, and configuration guides
- Testing docs with prose, examples, and tips
- GitHub Pages deployment for docs
### Changed
- Reworked homepage prose
- Rewrote CLI and API reference docs
## [v3.2.0] - 2026-03-22
### Added
- Pydantic auto-validation: `request_model` validates input, returns 422 on failure
- Pydantic auto-serialization: `response_model` strips extra fields from responses
- Server-Sent Events: `@resp.sse` for real-time streaming
- `resp.stream_file()` for streaming large files without loading into memory
- `@api.after_request()` hooks
- `api.group("/prefix")` for route groups and API versioning
- `api.graphql("/path", schema=schema)` one-liner GraphQL setup
- `api = responder.API(request_id=True)` for automatic request ID generation
- Built-in rate limiter: `RateLimiter(requests=100, period=60).install(api)`
- MessagePack format support: `await req.media("msgpack")`
- `req.is_json`, `req.path_params`, `req.client` properties
- `api.exception_handler()` decorator for custom error handling
- Lifespan context manager support
- `uuid` and `path` route convertors
- PEP 561 `py.typed` marker
- Pydantic support for OpenAPI schema generation
### Changed
- Dependencies flattened: `pip install responder` gets everything
- Core deps reduced to starlette + uvicorn
- TestClient lazy-loaded (no httpx import in production)
- Before-request hooks can short-circuit by setting status code
- Removed poethepoet task runner
### Fixed
- Multipart parser losing headers when parts have multiple headers
- `url_for()` with typed route params (`{id:int}`)
- `resp.body` encoding crash on bytes content
- GraphQL text query missing `await`
- Streaming responses not sending Content-Type headers
- Python 3.9 compatibility for union type syntax
## [v3.0.0] - 2026-03-22
@@ -373,7 +491,11 @@ this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
- Conception!
[unreleased]: https://github.com/kennethreitz/responder/compare/v3.0.0..HEAD
[v3.6.0]: https://github.com/kennethreitz/responder/compare/v3.5.0..v3.6.0
[v3.5.0]: https://github.com/kennethreitz/responder/compare/v3.4.0..v3.5.0
[v3.4.0]: https://github.com/kennethreitz/responder/compare/v3.3.0..v3.4.0
[v3.3.0]: https://github.com/kennethreitz/responder/compare/v3.2.0..v3.3.0
[v3.2.0]: https://github.com/kennethreitz/responder/compare/v3.0.0..v3.2.0
[v3.0.0]: https://github.com/kennethreitz/responder/compare/v2.0.5..v3.0.0
[v2.0.5]: https://github.com/kennethreitz/responder/compare/v2.0.4..v2.0.5
[v2.0.4]: https://github.com/kennethreitz/responder/compare/v2.0.3..v2.0.4
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# Responder
A familiar HTTP Service Framework for Python, by Kenneth Reitz.
## Commands
- **Tests**: `uv run pytest` (runs full suite with coverage)
- **Single test**: `uv run pytest tests/test_responder.py::test_name -xvs`
- **Lint**: `uv run ruff check .`
- **Type check**: `uv run mypy`
- **Build docs**: `cd docs && uv run make html`
- **Build package**: `uv build`
- **Lock deps**: `uv lock`
## Architecture
- `responder/api.py` — Main `API` class, the entry point for all apps
- `responder/routes.py``Router`, `Route`, `WebSocketRoute` dispatch
- `responder/models.py``Request` and `Response` wrappers around Starlette
- `responder/ext/` — Extensions: CLI, GraphQL, OpenAPI, rate limiting
- `responder/background.py` — Background task queue
- `responder/formats.py` — Content negotiation (JSON, YAML, msgpack)
- `responder/__version__.py` — Single source of truth for version string
## Conventions
- Python 3.10+ only. Use `from __future__ import annotations` where present.
- Use `inspect.iscoroutinefunction` (not `asyncio.iscoroutinefunction`).
- Tests use `api.requests` (Starlette TestClient) with `allowed_hosts=[";"]` or `["localhost"]`.
- Werkzeug 3.1.7+ rejects invalid Host headers — use `localhost` when mounting WSGI apps in tests.
- Version is in `responder/__version__.py`, bump it there.
- Changelog follows [Keep a Changelog](https://keepachangelog.com/) format in `CHANGELOG.md`.
- Compare links at the bottom of CHANGELOG.md must be updated when adding a release.
- All deps managed via `uv`. Lock file (`uv.lock`) is not committed.
## Release Process
1. Bump version in `responder/__version__.py`
2. Add changelog entry in `CHANGELOG.md` (update compare links too)
3. `uv lock` to refresh the lock file
4. Commit: `Bump version to X.Y.Z and update changelog`
5. `git tag vX.Y.Z && git push && git push origin vX.Y.Z`
6. `gh release create vX.Y.Z --title "vX.Y.Z" --notes "..."`
7. `uv build && uvx twine upload dist/responder-X.Y.Z*`
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@@ -17,7 +17,7 @@ if __name__ == "__main__":
$ pip install responder
That's it. Supports Python 3.9+.
That's it. Supports Python 3.10+.
## The Basics
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</p>
<p>
<strong>Responder</strong> — a familiar HTTP service framework for Python.
<br />
<small>v{{ version }}</small>
</p>
<h3>Useful Links</h3>
<ul>
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API Reference
=============
API Documentation
=================
This page documents Responder's public Python API. For usage examples
and explanations, see the :doc:`quickstart` and :doc:`tour`.
Web Service (API) Class
-----------------------
The API Class
-------------
The central object of every Responder application. It holds your routes,
middleware, templates, and configuration. Create one at the top of your
module and use it to define your entire web service.
Quick example::
import responder
api = responder.API(
title="My Service", # OpenAPI title
version="1.0", # OpenAPI version
openapi="3.0.2", # enable OpenAPI
docs_route="/docs", # Swagger UI at /docs
cors=True, # enable CORS
secret_key="change-me", # session signing key
allowed_hosts=["example.com"],
)
.. module:: responder
.. autoclass:: API
:inherited-members:
Requests & Responses
--------------------
Request
-------
The request object is passed into every view as the first argument. It
gives you access to everything the client sent — headers, query
parameters, the request body, cookies, and more.
Most properties are synchronous, but reading the body requires ``await``
because it involves I/O.
Common patterns::
# Headers (case-insensitive)
token = req.headers.get("Authorization")
# Query parameters: /search?q=python&page=2
query = req.params["q"]
# JSON body
data = await req.media()
# Form data
form = await req.media("form")
# File uploads
files = await req.media("files")
# Client info
ip, port = req.client
is_https = req.is_secure
.. autoclass:: Request
:inherited-members:
Response
--------
The response object is passed into every view as the second argument.
Mutate it to control what gets sent back to the client — the body,
status code, headers, and cookies.
Common patterns::
resp.text = "plain text" # text/plain
resp.html = "<h1>Hello</h1>" # text/html
resp.media = {"key": "value"} # application/json
resp.content = b"raw bytes" # application/octet-stream
resp.file("path/to/file.pdf") # auto content-type
resp.stream_file("large/export.csv") # streamed
resp.status_code = 201
resp.headers["X-Custom"] = "value"
resp.cookies["session"] = "abc123"
.. autoclass:: Response
:inherited-members:
Utility Functions
-----------------
Route Groups
------------
.. autofunction:: responder.API.status_codes.is_100
Group related routes under a shared URL prefix — useful for API versioning
and organizing large applications::
.. autofunction:: responder.API.status_codes.is_200
v1 = api.group("/v1")
.. autofunction:: responder.API.status_codes.is_300
@v1.route("/users")
def list_users(req, resp):
resp.media = []
.. autofunction:: responder.API.status_codes.is_400
.. autoclass:: responder.api.RouteGroup
:members:
.. autofunction:: responder.API.status_codes.is_500
Background Queue
----------------
Run tasks in background threads without blocking the response. Available
as ``api.background``::
@api.route("/submit")
async def submit(req, resp):
data = await req.media()
@api.background.task
def process(data):
# runs in a thread pool
...
process(data)
resp.media = {"status": "accepted"}
.. autoclass:: responder.background.BackgroundQueue
:members:
Query Dict
----------
A dictionary subclass for query string parameters with multi-value support.
Behaves like a normal dict for single values, but supports ``getlist()``
for parameters that appear multiple times (e.g. ``?tag=a&tag=b``).
.. autoclass:: responder.models.QueryDict
:members:
Rate Limiter
------------
In-memory token bucket rate limiter. Limits requests per client IP address
and returns ``429 Too Many Requests`` when exceeded::
from responder.ext.ratelimit import RateLimiter
limiter = RateLimiter(requests=100, period=60) # 100 req/min
limiter.install(api)
Response headers: ``X-RateLimit-Limit``, ``X-RateLimit-Remaining``,
and ``Retry-After`` (when limited).
.. autoclass:: responder.ext.ratelimit.RateLimiter
:members:
Status Code Helpers
-------------------
Convenience functions for checking which category a status code falls
into. Useful in middleware and after-request hooks::
from responder.status_codes import is_200, is_400, is_500
@api.after_request()
def log_errors(req, resp):
if is_400(resp.status_code) or is_500(resp.status_code):
print(f"Error: {req.method} {req.url.path} -> {resp.status_code}")
.. autofunction:: responder.status_codes.is_100
.. autofunction:: responder.status_codes.is_200
.. autofunction:: responder.status_codes.is_300
.. autofunction:: responder.status_codes.is_400
.. autofunction:: responder.status_codes.is_500
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# Backlog
## Future Ideas
- Consider adding `after_request` hooks (complement to `before_request`)
- Explore WebSocket before_request short-circuit support
- Add rate limiting middleware
- Consider async template rendering by default
- WebSocket before_request short-circuit support (reject before accept)
- Per-route rate limiting (different limits for different endpoints)
- Built-in structured logging with request context
- OpenAPI 3.1 support
- Dependency injection for route handlers
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Responder CLI
=============
Command Line Interface
======================
Responder installs a command line program ``responder``. Use it to launch
a Responder application from a file or module, either located on a local
or remote filesystem, or object store.
Launch Module Entrypoint
------------------------
For loading a Responder application from a Python module, you will refer to
its ``API()`` instance using a `Python entry point object reference`_ that
points to a Python object. It is either in the form ``importable.module``,
or ``importable.module:object.attr``.
A basic invocation command to launch a Responder application:
.. code-block:: shell
responder run acme.app
The command above assumes a Python package ``acme`` including an ``app``
module ``acme/app.py`` that includes an attribute ``api`` that refers
to a ``responder.API`` instance, reflecting the typical layout of
a standard Responder application.
Loading a Responder application using an entrypoint specification will
inherit the capacities of `Python's import system`_, as implemented by
`importlib`_.
Launch Local File
-----------------
Acquire a minimal example single-file application, ``helloworld.py`` [1]_,
to your local filesystem, giving you the chance to edit it, and launch the
Responder HTTP service.
.. code-block:: shell
wget https://github.com/kennethreitz/responder/raw/refs/heads/main/examples/helloworld.py
responder run helloworld.py
.. note::
To validate the example application, invoke a HTTP request, for example using
`curl`_, `HTTPie`_, or your favourite browser at hand.
.. code-block:: shell
http http://127.0.0.1:5042/Hello
The response is no surprise.
::
HTTP/1.1 200 OK
content-length: 13
content-type: text/plain
date: Sat, 26 Oct 2024 13:16:55 GMT
encoding: utf-8
server: uvicorn
Hello, world!
.. [1] The Responder application `helloworld.py`_ implements a basic echo handler.
Launch Remote File
------------------
You can also launch a single-file application where its Python file is stored
on a remote location.
Responder supports all filesystem adapters compatible with `fsspec`_, and
installs the adapters for Azure Blob Storage (az), Google Cloud Storage (gs),
GitHub, HTTP, and AWS S3 by default.
.. code-block:: shell
# Works 1:1.
responder run https://github.com/kennethreitz/responder/raw/refs/heads/main/examples/helloworld.py
responder run github://kennethreitz:responder@/examples/helloworld.py
If you need access other kinds of remote targets, see the `list of
fsspec-supported filesystems and protocols`_. The next section enumerates
a few synthetic examples. The corresponding storage buckets do not even
exist, so don't expect those commands to work.
.. code-block:: shell
# Azure Blob Storage, Google Cloud Storage, and AWS S3.
responder run az://kennethreitz-assets/responder/examples/helloworld.py
responder run gs://kennethreitz-assets/responder/examples/helloworld.py
responder run s3://kennethreitz-assets/responder/examples/helloworld.py
# Hadoop Distributed File System (hdfs), SSH File Transfer Protocol (sftp),
# Common Internet File System (smb), Web-based Distributed Authoring and
# Versioning (webdav).
responder run hdfs://kennethreitz-assets/responder/examples/helloworld.py
responder run sftp://user@host/kennethreitz/responder/examples/helloworld.py
responder run smb://workgroup;user:password@server:port/responder/examples/helloworld.py
responder run webdav+https://user:password@server:port/responder/examples/helloworld.py
.. tip::
In order to install support for all filesystem types supported by fsspec, run:
.. code-block:: shell
uv pip install 'fsspec[full]'
When using ``uv``, this concludes within an acceptable time of approx.
25 seconds. If you need to be more selectively instead of using ``full``,
choose from one or multiple of the available `fsspec extras`_, which are:
abfs, arrow, dask, dropbox, fuse, gcs, git, github, hdfs, http, oci, s3,
sftp, smb, ssh.
Launch with Non-Standard Instance Name
--------------------------------------
By default, Responder will acquire an ``responder.API`` instance using the
symbol name ``api`` from the specified Python module.
If your main application file uses a different name than ``api``, please
append the designated symbol name to the launch target address.
It works like this for module entrypoints and local files:
.. code-block:: shell
responder run acme.app:service
responder run /path/to/acme/app.py:service
It works like this for URLs:
.. code-block:: shell
responder run http://app.server.local/path/to/acme/app.py#service
Within your ``app.py``, the instance would have been defined to use
the ``service`` symbol name instead of ``api``, like this:
.. code-block:: python
service = responder.API()
Build JavaScript Application
----------------------------
The ``build`` subcommand invokes ``npm run build``, optionally accepting
a target directory. By default, it uses the current working directory,
where it expects a regular NPM ``package.json`` file.
.. code-block:: shell
responder build
When specifying a target directory, Responder will change to that
directory beforehand.
.. code-block:: shell
responder build /path/to/project
Responder installs a ``responder`` command that lets you launch
applications from the terminal. You can point it at a Python module,
a local file, or even a URL — and it will find your ``API`` instance
and start serving.
.. _curl: https://curl.se/
.. _fsspec: https://filesystem-spec.readthedocs.io/en/latest/
.. _fsspec extras: https://github.com/fsspec/filesystem_spec/blob/2024.12.0/pyproject.toml#L27-L69
.. _helloworld.py: https://github.com/kennethreitz/responder/blob/main/examples/helloworld.py
.. _HTTPie: https://httpie.io/docs/cli
.. _importlib: https://docs.python.org/3/library/importlib.html
.. _list of fsspec-supported filesystems and protocols: https://github.com/fsspec/universal_pathlib#currently-supported-filesystems-and-protocols
.. _Python entry point object reference: https://packaging.python.org/en/latest/specifications/entry-points/
.. _Python's import system: https://docs.python.org/3/reference/import.html
Launching from a Module
-----------------------
The most common way to run a Responder application in production. Use
Python's standard dotted module path::
$ responder run acme.app
This imports ``acme.app`` and looks for an attribute called ``api``
(a ``responder.API`` instance). It's the same import system Python
uses everywhere — your ``PYTHONPATH`` and virtual environment are
respected.
Launching from a File
---------------------
During development, you often have a single file you want to run::
$ responder run helloworld.py
This loads the file directly and starts the server. Quick and easy for
prototyping and single-file applications.
You can test it with a simple HTTP request::
$ curl http://127.0.0.1:5042/hello
hello, world!
Launching from a URL
--------------------
Responder can fetch and run a Python file from any URL — great for
demos, sharing examples, and running code from GitHub::
$ responder run https://github.com/kennethreitz/responder/raw/refs/heads/main/examples/helloworld.py
This also works with ``github://`` URLs and any filesystem protocol
supported by `fsspec <https://filesystem-spec.readthedocs.io/>`_::
$ responder run github://kennethreitz:responder@/examples/helloworld.py
Cloud storage is supported too — Azure Blob Storage, Google Cloud
Storage, S3, HDFS, SFTP, and more. Install ``fsspec[full]`` for all
protocols::
$ uv pip install 'fsspec[full]'
Custom Instance Names
---------------------
By default, Responder looks for an attribute called ``api``. If your
application uses a different name, specify it with a colon::
$ responder run acme.app:service
$ responder run myapp.py:application
For URLs, use a fragment::
$ responder run https://example.com/app.py#service
Environment Variables
---------------------
Responder automatically reads the ``PORT`` environment variable at
runtime:
- ``PORT`` — bind to ``0.0.0.0`` on this port (cloud platform convention)
When ``PORT`` is set, the server binds to all interfaces automatically.
This is how cloud platforms like Fly.io, Railway, and Heroku inject the
listen port.
For other settings like ``SECRET_KEY``, read them in your application
code and pass them to ``responder.API()``::
import os
api = responder.API(secret_key=os.environ["SECRET_KEY"])
Building Frontend Assets
-------------------------
If your project includes a JavaScript frontend with a ``package.json``,
the ``build`` subcommand runs ``npm run build``::
$ responder build
$ responder build /path/to/frontend
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Deployment
==========
Responder applications are standard ASGI apps. You can deploy them anywhere
you'd deploy a Python web service.
Responder applications are standard `ASGI <https://asgi.readthedocs.io/>`_
apps. ASGI (Asynchronous Server Gateway Interface) is the modern successor
to WSGI — it supports async, WebSockets, and HTTP/2. This means you can
deploy a Responder app anywhere that runs Python, using any ASGI server.
Running Locally
---------------
The simplest way to run your application::
# api.py
import responder
api = responder.API()
@api.route("/")
def hello(req, resp):
resp.text = "hello, world!"
During development, ``api.run()`` is all you need::
if __name__ == "__main__":
api.run()
This starts a production uvicorn server on ``127.0.0.1:5042``.
This starts a `uvicorn <https://www.uvicorn.org/>`_ server on
``127.0.0.1:5042``. Uvicorn is a lightning-fast ASGI server built on
`uvloop <https://uvloop.readthedocs.io/>`_ — it handles thousands of
concurrent connections efficiently and protects against slowloris attacks,
making a reverse proxy like nginx optional for many deployments.
Docker
------
A minimal Dockerfile for deploying a Responder application::
Docker is the most common way to package and deploy web applications.
Here's a minimal Dockerfile::
FROM python:3.13-slim
WORKDIR /app
COPY --from=ghcr.io/astral-sh/uv:latest /uv /usr/local/bin/uv
COPY . .
RUN pip install responder
RUN uv pip install --system responder
ENV PORT=80
EXPOSE 80
CMD ["python", "api.py"]
@@ -43,44 +42,146 @@ Build and run::
$ docker build -t myapi .
$ docker run -p 8000:80 myapi
The ``python:3.13-slim`` image is about 150MB — small enough for fast
deploys but includes everything you need. Using ``uv`` for installs
is significantly faster than pip. For even smaller images, you can use
``python:3.13-alpine``, though some packages may need extra build
dependencies.
Cloud Platforms
---------------
Responder automatically honors the ``PORT`` environment variable, which is
set by most cloud platforms. When ``PORT`` is set, Responder binds to
``0.0.0.0`` on that port automatically.
Responder automatically honors the ``PORT`` environment variable. When
``PORT`` is set, the server binds to ``0.0.0.0`` on that port — this is
the convention that virtually every cloud platform uses.
This works out of the box with:
This means zero configuration on:
- **Fly.io**
- **Railway**
- **Render**
- **Google Cloud Run**
- **Azure Container Apps**
- **AWS App Runner**
- **Fly.io**``fly launch`` and you're done
- **Railway** — push your code, Railway sets ``PORT``
- **Render** — set start command to ``python api.py``
- **Google Cloud Run** — containerize and deploy
- **Azure Container Apps** — same pattern
- **AWS App Runner** — and here too
Just deploy your code and set the start command to ``python api.py``.
The pattern is always the same: deploy your code, set the start command
to ``python api.py``, and the platform handles the rest.
Health Check Endpoint
---------------------
Every production deployment needs a health check — a lightweight endpoint
that monitoring tools, load balancers, and orchestrators can poll to verify
your service is running::
@api.route("/health")
def health(req, resp):
resp.media = {"status": "healthy"}
Keep it simple. Don't query the database or do expensive work — the health
check should return instantly. Cloud platforms, Docker, and Kubernetes all
look for an HTTP 200 to confirm your service is alive.
For Docker, add a ``HEALTHCHECK`` instruction::
HEALTHCHECK --interval=30s --timeout=3s \
CMD curl -f http://localhost/health || exit 1
Uvicorn Directly
----------------
For more control over the production server, you can bypass ``api.run()``
and use uvicorn directly::
For production deployments where you want more control, bypass
``api.run()`` and use uvicorn directly::
$ uvicorn api:api --host 0.0.0.0 --port 8000 --workers 4
This gives you access to all of uvicorn's options: worker count, SSL
certificates, access logging, and more. See the
`uvicorn documentation <https://www.uvicorn.org/>`_ for details.
The ``--workers`` flag spawns multiple processes, each handling requests
independently. A good starting point is 2-4 workers per CPU core.
Uvicorn supports many options — SSL certificates, access logging, graceful
shutdown timeouts, and more. See the
`uvicorn documentation <https://www.uvicorn.org/deployment/>`_ for details.
For platforms like Heroku or Railway that use a ``Procfile``::
web: uvicorn api:api --host 0.0.0.0 --port $PORT --workers 4
Docker Compose
--------------
For local development with databases and other services, Docker Compose
ties everything together::
# docker-compose.yml
services:
api:
build: .
ports:
- "5042:80"
environment:
- PORT=80
- DATABASE_URL=postgresql+asyncpg://user:pass@db/myapp
- SECRET_KEY=dev-secret
depends_on:
- db
db:
image: docker.io/postgres:16-alpine
environment:
POSTGRES_USER: user
POSTGRES_PASSWORD: pass
POSTGRES_DB: myapp
volumes:
- pgdata:/var/lib/postgresql/data
volumes:
pgdata:
Run with ``docker compose up``. The API waits for ``db`` to start, then
connects using the ``DATABASE_URL`` environment variable.
Reverse Proxy
-------------
In production, you may want to place Responder behind a reverse proxy like
nginx or Caddy for SSL termination, load balancing, or serving static assets.
For high-traffic production deployments, you may want a reverse proxy like
`nginx <https://nginx.org/>`_ or `Caddy <https://caddyserver.com/>`_ in
front of your application for:
- **SSL/TLS termination** — let the proxy handle HTTPS certificates
- **Load balancing** — distribute traffic across multiple app instances
- **Static asset serving** — offload static files to the proxy
- **Rate limiting** — at the infrastructure level
A minimal Caddy config that handles HTTPS automatically::
# Caddyfile
example.com {
reverse_proxy localhost:5042
}
Responder's ``TrustedHostMiddleware`` and ``HTTPSRedirectMiddleware`` work
correctly behind proxies that set standard forwarding headers.
correctly behind proxies that set standard forwarding headers
(``X-Forwarded-For``, ``X-Forwarded-Proto``).
That said, uvicorn is production-ready on its own. Many applications run
uvicorn directly without a reverse proxy and do just fine.
Production Checklist
--------------------
Before going live:
- **Set a secret key**``SECRET_KEY`` env var, never the default
- **Disable debug mode**``DEBUG=false`` or omit it entirely
- **Set allowed hosts** — restrict to your actual domain names
- **Use multiple workers**``--workers 4`` or more, depending on CPU cores
- **Add a health check**``/health`` endpoint for monitoring
- **Enable HTTPS** — via your proxy, cloud platform, or uvicorn's ``--ssl-*`` flags
- **Set up logging** — uvicorn logs requests by default; pipe them to your log aggregator
- **Pin your dependencies** — use a lock file or pinned requirements for reproducible deploys
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Configuration
=============
Every application needs different settings for different environments —
debug mode in development, real secrets in production, different database
URLs for testing. This guide covers how to manage configuration cleanly.
Environment Variables
---------------------
The simplest and most universal approach. Environment variables work
everywhere — locally, in Docker, on cloud platforms — and keep secrets
out of your source code::
import os
import responder
api = responder.API(
debug=os.getenv("DEBUG", "false").lower() == "true",
secret_key=os.environ["SECRET_KEY"],
cors=os.getenv("CORS_ENABLED", "false").lower() == "true",
)
Some variables Responder handles automatically:
- ``PORT`` — when set, the server binds to ``0.0.0.0`` on this port
Set variables in your shell::
$ export SECRET_KEY="your-secret-here"
$ export DEBUG=true
$ python app.py
Or in a ``.env`` file (don't commit this to git)::
SECRET_KEY=your-secret-here
DEBUG=true
Using .env Files
----------------
For local development, a ``.env`` file is convenient. Install
``python-dotenv`` and load it at the top of your app::
$ uv pip install python-dotenv
::
from dotenv import load_dotenv
load_dotenv()
import os
import responder
api = responder.API(
secret_key=os.environ["SECRET_KEY"],
)
Add ``.env`` to your ``.gitignore`` — never commit secrets.
Configuration Class Pattern
----------------------------
For larger applications, a configuration class keeps things organized::
import os
class Config:
SECRET_KEY = os.environ.get("SECRET_KEY", "dev-secret")
DEBUG = os.environ.get("DEBUG", "false").lower() == "true"
DATABASE_URL = os.environ.get("DATABASE_URL", "sqlite:///dev.db")
CORS_ORIGINS = os.environ.get("CORS_ORIGINS", "").split(",")
config = Config()
api = responder.API(
debug=config.DEBUG,
secret_key=config.SECRET_KEY,
cors=bool(config.CORS_ORIGINS[0]),
cors_params={"allow_origins": config.CORS_ORIGINS},
)
This makes it easy to see all your settings in one place.
Secret Key
----------
The ``secret_key`` is used to sign session cookies. If someone knows your
secret key, they can forge session data and impersonate any user.
Rules:
- **Never use the default** in production
- **Generate a random key**: ``python -c "import secrets; print(secrets.token_hex(32))"``
- **Store it in an environment variable**, not in code
- **Rotate it** if it's ever compromised (this invalidates all sessions)
::
api = responder.API(secret_key=os.environ["SECRET_KEY"])
Debug Mode
----------
Debug mode controls error page behavior:
- **On** (``debug=True``): detailed error pages with tracebacks. Never
use this in production — it exposes your source code.
- **Off** (``debug=False``): generic error pages. This is the default.
::
api = responder.API(debug=True) # development only
A common pattern is to read it from the environment::
api = responder.API(debug=os.getenv("DEBUG") == "true")
Allowed Hosts
-------------
In production, always set ``allowed_hosts`` to prevent Host header
attacks. This should match the domain names your application serves::
api = responder.API(
allowed_hosts=["example.com", "www.example.com"],
)
In development, you can use ``["*"]`` (the default) or specific local
addresses::
api = responder.API(allowed_hosts=["localhost", "127.0.0.1"])
Putting It All Together
-----------------------
A production-ready configuration setup::
import os
from dotenv import load_dotenv
load_dotenv()
import responder
api = responder.API(
debug=os.getenv("DEBUG", "false") == "true",
secret_key=os.environ["SECRET_KEY"],
allowed_hosts=os.getenv("ALLOWED_HOSTS", "*").split(","),
cors=bool(os.getenv("CORS_ORIGINS")),
cors_params={
"allow_origins": os.getenv("CORS_ORIGINS", "").split(","),
"allow_methods": ["GET", "POST", "PUT", "DELETE"],
},
)
With a ``.env`` file for local development::
SECRET_KEY=dev-secret-do-not-use-in-prod
DEBUG=true
ALLOWED_HOSTS=localhost,127.0.0.1
CORS_ORIGINS=http://localhost:3000
And environment variables set properly in production (via your cloud
platform's dashboard, Docker secrets, or a secrets manager).
+46 -22
View File
@@ -16,36 +16,42 @@ A familiar HTTP Service Framework for Python.
if __name__ == '__main__':
api.run()
Powered by `Starlette`_ and `uvicorn`_. The ``async`` is optional.
Powered by `Starlette`_, `uvicorn`_, and good intentions. The ``async`` is optional.
The Idea
--------
Responder takes the best ideas from `Flask`_ and `Falcon`_ and brings them
together into one clean framework.
If you've ever used `Flask`_, the routing will look familiar. If you've
used `Falcon`_, the request/response pattern will click immediately. And
if you've used `Requests`_ — well, you'll feel right at home.
The request and response objects are passed into every view and mutated
directly — no return values, no boilerplate. If you've used Requests,
you'll feel right at home. If you've used Flask, the routing will look
familiar. If you've used Falcon, the ``req`` / ``resp`` pattern will
click immediately.
Responder takes these ideas and brings them together. Every view receives
a request and a response. You read from one and write to the other. No
return values, no special response classes, no boilerplate.
- ``resp.text`` sends back text. ``resp.html`` sends back HTML.
- ``resp.media`` sends back JSON — or YAML, if the client asks for it.
- ``resp.text`` sends text. ``resp.html`` sends HTML. ``resp.media`` sends JSON.
- ``resp.file("path")`` serves a file. ``resp.content`` sends raw bytes.
- ``req.headers`` is case-insensitive. ``req.params`` holds query parameters.
- ``resp.status_code``, ``req.method``, ``req.url`` — the usual suspects.
- ``resp.status_code``, ``req.method``, ``req.url`` — the familiar ones.
Content negotiation happens automatically. Set ``resp.media`` to a dict
and Responder figures out the rest.
Set ``resp.media`` to a dict and the right thing happens. If the client
asks for YAML, it gets YAML. Content negotiation is automatic.
Responder and `FastAPI`_ share DNA — both are built on Starlette, both
appeared around the same time, and both pushed Python's ASGI ecosystem
forward. FastAPI went deep on type annotations and automatic validation.
Responder went for a mutable request/response pattern and a simpler,
more familiar API. Both projects are better for the other existing, and
you should use whichever feels right for what you're building.
Responder and `FastAPI`_ are siblings — both built on Starlette, both
born around the same time, both part of the push that made ASGI the
future of Python web services. FastAPI went deep on type annotations
and automatic validation. Responder went for simplicity and a mutable
request/response pattern. Both projects are better for the other
existing. Use whichever feels right.
This is a passion project. It exists because building a web framework
from scratch is one of the best ways to understand how the web works.
It's a great fit for personal projects, prototyping, teaching, research,
and anyone who values a clean API over a sprawling ecosystem. If you
need battle-tested infrastructure at scale, FastAPI and Django will
serve you well. If you want something small, expressive, and fun to
work with — welcome.
What You Get
@@ -53,21 +59,26 @@ What You Get
One ``pip install``, batteries included:
- Pydantic request validation and response serialization.
- Mount Flask, Django, or any WSGI/ASGI app at a subroute.
- Gzip compression, HSTS, CORS, and trusted host validation.
- Before-request hooks that can short-circuit for auth guards.
- Before-request and after-request hooks for auth and logging.
- A test client for fast, in-process testing with pytest.
- Route parameters with f-string syntax and type convertors.
- Lifespan context managers for startup and shutdown logic.
- Custom exception handlers for clean error responses.
- `GraphQL`_ with Graphene and a built-in GraphiQL IDE.
- Server-Sent Events for real-time streaming.
- File serving with automatic content-type detection.
- Sync and async views — ``async`` is always optional.
- Class-based views with ``on_get``, ``on_post``, ``on_request``.
- Built-in rate limiting with ``X-RateLimit`` headers.
- Structured logging with per-request context.
- Content negotiation: JSON, YAML, and MessagePack.
- A pleasant API with a single import statement.
- OpenAPI schema generation with Swagger UI.
- A production `uvicorn`_ server, ready to deploy.
- HTTP method filtering for REST APIs.
- Route groups for API versioning.
- Signed cookie-based sessions.
- Background tasks in a thread pool.
- WebSocket support.
@@ -80,7 +91,7 @@ Installation
$ uv pip install responder
Python 3.9 and above. That's it.
Python 3.10 and above. That's it.
.. toctree::
@@ -94,6 +105,18 @@ Python 3.9 and above. That's it.
api
cli
.. toctree::
:maxdepth: 2
:caption: Tutorials
tutorial-rest
tutorial-sqlalchemy
tutorial-auth
tutorial-websockets
tutorial-middleware
tutorial-flask
guide-config
.. toctree::
:maxdepth: 1
:caption: Project
@@ -109,3 +132,4 @@ Python 3.9 and above. That's it.
.. _Falcon: https://falconframework.org/
.. _FastAPI: https://fastapi.tiangolo.com/
.. _GraphQL: https://graphql.org/
.. _Requests: https://requests.readthedocs.io/
+207 -57
View File
@@ -2,164 +2,229 @@ Quick Start
===========
This guide will walk you through the basics of building a web service with
Responder. By the end, you'll know how to declare routes, handle requests,
send responses, render templates, and process background tasks.
Responder. By the end, you'll understand how HTTP requests and responses
work, how to define routes, read data from clients, send data back, render
HTML templates, and process work in the background.
Create a Web Service
--------------------
The first thing you need to do is declare a web service. This is the central
object that holds all your routes, middleware, and configuration::
Every web application starts with a single object — the application
instance. In Responder, this is the ``API`` class. It holds your routes,
middleware, templates, and configuration. Think of it as the central
nervous system of your web service::
import responder
api = responder.API()
That's it. One import, one line. You now have a fully functional ASGI
application with gzip compression, static file serving, session support,
and a production-ready server — all wired up and ready to go.
Hello World
-----------
Next, add a route. Here, we'll make the root URL say "hello, world!"::
A web service isn't very useful until it can respond to requests. In HTTP,
a *route* maps a URL path to a function that handles it. When a client
(like a browser or ``curl``) sends a request to that path, your function
runs and produces a response.
Here's the simplest possible route::
@api.route("/")
def hello_world(req, resp):
resp.text = "hello, world!"
Every view receives a ``req`` (request) and ``resp`` (response) object. You
don't need to return anything — just mutate the response directly.
Two things to notice:
1. Every view function receives two arguments: ``req`` (the incoming
request) and ``resp`` (the outgoing response).
2. You don't return anything. Instead, you *mutate* the response object
directly. This is a deliberate design choice — it keeps the API
consistent whether you're setting text, JSON, headers, cookies, or
status codes.
Run the Server
--------------
Start your web service with ``api.run()``::
Start your web service with a single call::
api.run()
This spins up a production-grade uvicorn server on port ``5042``, ready for
incoming HTTP requests.
This spins up a production-grade `uvicorn <https://www.uvicorn.org/>`_
server on port ``5042``, ready for incoming HTTP requests. Open
``http://localhost:5042`` in your browser and you'll see your hello world
response.
You can customize the port with ``api.run(port=8000)``. The ``PORT``
environment variable is also honored automatically — when set, Responder
binds to ``0.0.0.0`` on that port, which is what cloud platforms like
Fly.io, Railway, and Google Cloud Run expect.
binds to ``0.0.0.0`` on that port, which is what cloud platforms expect.
.. note::
Both sync and async views are supported. The ``async`` keyword is always
optional — use it when you need to ``await`` something.
optional — use it when you need to ``await`` something, like reading a
request body or querying a database.
Route Parameters
----------------
If you want dynamic URLs, use Python's familiar f-string syntax to declare
variables in your routes::
Static URLs like ``/about`` are useful, but most applications need dynamic
routes — URLs that contain variable data, like a user ID or a product slug.
In Responder, you declare route parameters using Python's f-string syntax::
@api.route("/hello/{who}")
def hello_to(req, resp, *, who):
resp.text = f"hello, {who}!"
A ``GET`` request to ``/hello/world`` will respond with ``hello, world!``.
A request to ``/hello/guido`` will respond with ``hello, guido!``.
Route parameters are passed as keyword-only arguments (after the ``*``).
Route parameters are passed as *keyword-only* arguments (after the ``*``
in the function signature). This is a Python feature that makes the
interface explicit — you always know which arguments come from the URL.
Type Convertors
^^^^^^^^^^^^^^^
You can constrain route parameters to specific types. The parameter will be
automatically converted before it reaches your view::
By default, route parameters are strings. But often you want them as
integers, UUIDs, or other types. Responder can convert them automatically
using type annotations in the route pattern::
@api.route("/add/{a:int}/{b:int}")
async def add(req, resp, *, a, b):
resp.text = f"{a} + {b} = {a + b}"
Here, ``a`` and ``b`` will arrive as Python ``int`` objects, not strings.
If someone requests ``/add/3/hello``, they'll get a 404 — the route won't
match because ``hello`` isn't a valid integer.
Supported types:
- ``str`` — matches any string without slashes (default)
- ``int`` — matches digits, converts to ``int``
- ``float`` — matches decimal numbers, converts to ``float``
- ``str`` — matches any string without slashes (this is the default)
- ``int`` — matches digits and converts to ``int``
- ``float`` — matches decimal numbers and converts to ``float``
- ``uuid`` — matches UUID strings like ``550e8400-e29b-41d4-a716-446655440000``
- ``path`` — matches any string *including* slashes, useful for file paths
like ``/files/{filepath:path}``
Sending Responses
-----------------
Responder gives you several ways to send data back to the client. Just set
the appropriate property on the response object.
When an HTTP server receives a request, it must send back a response. Every
HTTP response has three parts: a status code (like ``200 OK`` or ``404 Not
Found``), headers (metadata like ``Content-Type``), and a body (the actual
data).
**Text and HTML**::
Responder lets you set all three by mutating the response object.
**Text and HTML** — the simplest response types. ``resp.text`` sets the
``Content-Type`` to ``text/plain``, while ``resp.html`` sets it to
``text/html``::
resp.text = "plain text response"
resp.html = "<h1>HTML response</h1>"
**JSON** — the most common pattern for APIs. Set ``resp.media`` to any
JSON-serializable Python object::
**JSON** — the lingua franca of web APIs. Set ``resp.media`` to any
JSON-serializable Python object — a dict, a list, whatever — and Responder
will serialize it to JSON and set the right headers::
@api.route("/hello/{who}/json")
def hello_json(req, resp, *, who):
resp.media = {"hello": who}
If the client sends an ``Accept: application/x-yaml`` header, the same data
will be returned as YAML instead. Content negotiation is automatic.
will be returned as YAML instead. This is called *content negotiation*
the server and client agree on a format. It happens automatically.
**Files** — serve a file from disk with automatic content-type detection::
**Files** — serve a file from disk. Responder uses Python's ``mimetypes``
module to figure out the ``Content-Type`` from the file extension::
resp.file("reports/annual.pdf")
**Raw bytes**::
**Raw bytes** — for binary data like images or protocol buffers::
resp.content = b"\x89PNG\r\n..."
**Status codes and headers**::
**Status codes** — HTTP status codes tell the client what happened. ``200``
means success, ``201`` means something was created, ``404`` means not found,
``500`` means the server broke. Set it directly::
resp.status_code = 201
**Headers** — HTTP headers carry metadata. Common ones include
``Content-Type``, ``Cache-Control``, ``Authorization``, and custom
application headers::
resp.headers["X-Custom"] = "value"
**Redirects**::
**Redirects** — tell the client to go somewhere else::
api.redirect(resp, location="/new-url")
This sends a ``301 Moved Permanently`` response by default. The client's
browser will automatically follow the redirect.
Reading Requests
----------------
The request object gives you access to everything the client sent.
The other half of HTTP is the request — the data the client sends to your
server. This includes the HTTP method (GET, POST, PUT, DELETE), the URL,
headers, query parameters, cookies, and optionally a body.
**Method and URL**::
Responder wraps all of this in the ``req`` object.
**Method and URL** — every HTTP request has a method (what the client wants
to do) and a URL (what resource it's about)::
req.method # "get", "post", etc. (lowercase)
req.full_url # "http://example.com/path?q=1"
req.url # parsed URL object
**Headers**case-insensitive, just like you'd expect::
**Headers**HTTP headers carry metadata from the client, like what
content types it accepts, authentication tokens, and more. Responder's
headers dict is case-insensitive, because the HTTP spec says header names
are case-insensitive::
req.headers["Content-Type"]
req.headers["content-type"] # same thing
**Query parameters**::
**Query parameters** — the part of the URL after the ``?``. These are
commonly used for search, filtering, and pagination::
# GET /search?q=python&page=2
req.params["q"] # "python"
req.params["page"] # "2"
**Path parameters** — also available on the request object::
Note that query parameters are always strings. If you need an integer,
you'll need to convert it yourself: ``int(req.params["page"])``.
**Path parameters** — the dynamic parts of the URL that matched your route
pattern. These are also available on the request object, which is useful
in before-request hooks where they aren't passed as function arguments::
req.path_params["user_id"] # same as the keyword argument
**Request body** — for POST/PUT/PATCH requests, you need to ``await`` the
body content::
**Request body** — for POST, PUT, and PATCH requests, the client sends
data in the body. Since reading the body is an I/O operation, you need to
``await`` it::
# JSON body
# JSON body (the most common format for APIs)
data = await req.media()
# Form data
# Form data (from HTML forms)
data = await req.media("form")
# File uploads
# File uploads (multipart)
files = await req.media("files")
# Raw bytes
@@ -170,41 +235,59 @@ body content::
**Other useful properties**::
req.is_json # True if content type is JSON
req.cookies # dict of cookies
req.session # session data (dict)
req.client # (host, port) tuple
req.is_secure # True if HTTPS
req.is_json # True if the content type is JSON
req.cookies # dict of cookies sent by the client
req.session # session data (a signed, server-side dict)
req.client # (host, port) tuple — the client's IP address
req.is_secure # True if the request came over HTTPS
Rendering Templates
-------------------
Responder includes built-in `Jinja2 <https://jinja.palletsprojects.com/>`_
support. Templates are loaded from the ``templates/`` directory by default.
While APIs typically return JSON, many web applications need to render
HTML pages. Responder includes built-in support for
`Jinja2 <https://jinja.palletsprojects.com/>`_, one of the most popular
templating engines in the Python ecosystem.
The simplest way is to use ``api.template()``::
Templates let you write HTML with placeholders that get filled in with
dynamic data. This keeps your presentation logic (HTML) separate from
your application logic (Python) — a pattern called
*separation of concerns*.
The simplest way to render a template is ``api.template()``. Templates
are loaded from the ``templates/`` directory by default::
@api.route("/hello/{name}/html")
def hello_html(req, resp, *, name):
resp.html = api.template("hello.html", name=name)
You can also use the ``Templates`` class directly for more control::
The template file ``templates/hello.html`` might look like::
<h1>Hello, {{ name }}!</h1>
The ``{{ name }}`` part is a Jinja2 expression — it gets replaced with
the value you passed in.
You can also use the ``Templates`` class directly for more control over
the template directory and configuration::
from responder.templates import Templates
templates = Templates(directory="templates")
templates = Templates(directory="my_templates")
@api.route("/page")
def page(req, resp):
resp.html = templates.render("page.html", title="Hello")
Async rendering is supported too::
For applications that need non-blocking template rendering (rare, but
useful under extreme load), async rendering is supported::
templates = Templates(directory="templates", enable_async=True)
resp.html = await templates.render_async("page.html", title="Hello")
You can render template strings without a file::
And for quick one-off templates, you can render a string directly without
a file::
resp.html = api.template_string("Hello, {{ name }}!", name="world")
@@ -213,7 +296,13 @@ Background Tasks
----------------
Sometimes you want to accept a request, respond immediately, and do the
actual processing later. Responder makes this easy with background tasks::
actual processing later. This is a common pattern for operations that take
a long time — sending emails, processing images, updating caches, or
calling slow external APIs.
Responder makes this easy with background tasks. Decorate any function
with ``@api.background.task`` and it will run in a thread pool, separate
from the request/response cycle::
@api.route("/incoming")
async def receive_incoming(req, resp):
@@ -227,8 +316,69 @@ actual processing later. Responder makes this easy with background tasks::
process_data(data)
# Respond immediately processing continues in the background
# This response is sent immediately, while process_data
# continues running in the background.
resp.media = {"status": "accepted"}
The ``@api.background.task`` decorator wraps any function to run in a thread
pool. The client gets an immediate response while the work continues.
The client gets an instant response — the heavy lifting happens after.
This is the same pattern used by task queues like Celery, but much simpler
for lightweight use cases where you don't need a full message broker.
.. note::
Background tasks run in threads, not processes. They share memory with
your application, which makes them fast to start but means CPU-intensive
work will block the event loop. For heavy computation, consider a proper
task queue.
Putting It All Together
-----------------------
Here's a complete, working Responder application that combines everything
from this guide::
import responder
api = responder.API()
@api.route("/")
def index(req, resp):
resp.text = "Welcome to the API"
@api.route("/hello/{name}")
def greet(req, resp, *, name):
resp.media = {"message": f"hello, {name}!"}
@api.route("/add/{a:int}/{b:int}")
def add(req, resp, *, a, b):
resp.media = {"result": a + b}
@api.route("/echo", methods=["POST"])
async def echo(req, resp):
data = await req.media()
resp.media = {"received": data}
if __name__ == "__main__":
api.run()
Save this as ``app.py``, run it with ``python app.py``, and try::
$ curl http://localhost:5042/
$ curl http://localhost:5042/hello/world
$ curl http://localhost:5042/add/3/4
$ curl -X POST http://localhost:5042/echo \
-H "Content-Type: application/json" -d '{"key": "value"}'
From here, explore the :doc:`tour` for the full range of features, or
jump into the tutorials:
- :doc:`tutorial-rest` — build a full CRUD API with validation
- :doc:`tutorial-sqlalchemy` — connect to a database
- :doc:`tutorial-auth` — add authentication
- :doc:`tutorial-websockets` — real-time communication
- :doc:`tutorial-middleware` — hooks and middleware
- :doc:`tutorial-flask` — migrating from Flask
- :doc:`guide-config` — environment variables and secrets
- :doc:`deployment` — Docker, cloud platforms, and production
- :doc:`testing` — writing tests with pytest
+43 -17
View File
@@ -2,35 +2,61 @@
# Development Sandbox
## Setup
Set up a development sandbox.
Acquire sources and create virtualenv.
Clone the repo and install all dependencies:
```shell
git clone https://github.com/kennethreitz/responder.git
cd responder
uv venv
```
Install project in editable mode, including
all development tools.
```shell
uv venv && source .venv/bin/activate
uv pip install --upgrade --editable '.[develop,docs,release,test]'
```
## Operations
Run tests.
## Running Tests
```shell
source .venv/bin/activate
pytest
pytest # full suite with coverage
pytest tests/test_responder.py -xvs # single file, stop on first failure
pytest -k "test_mount" # run tests matching a pattern
```
Format code.
## Code Formatting
```shell
ruff format .
ruff check --fix .
ruff format . # auto-format
ruff check --fix . # lint and auto-fix
```
Documentation authoring.
## Type Checking
```shell
sphinx-autobuild --open-browser --watch docs/source docs/source docs/build
mypy
```
## Documentation
Live-reloading doc server (opens in browser):
```shell
cd docs
sphinx-autobuild --open-browser --watch source source build
```
Or build once:
```shell
cd docs
make html
# open build/html/index.html
```
## Project Layout
```
responder/
├── responder/ # main package
│ ├── api.py # API class — the entry point
│ ├── routes.py # Router, Route, WebSocketRoute
│ ├── models.py # Request and Response wrappers
│ ├── ext/ # extensions (CLI, GraphQL, OpenAPI, rate limiting)
│ ├── background.py # background task queue
│ └── formats.py # content negotiation (JSON, YAML, msgpack)
├── tests/ # pytest test suite
├── examples/ # runnable example apps
├── docs/source/ # Sphinx documentation
└── pyproject.toml # project metadata and tool config
```
+197 -14
View File
@@ -3,7 +3,9 @@ Testing
Responder includes a built-in test client powered by Starlette's
``TestClient``. You don't need to start a server — tests run in-process,
making them fast and reliable.
making them fast and reliable. There's no separate test server to manage,
no ports to allocate, and no race conditions to worry about. Just import
your app and start making requests.
Getting Started
@@ -22,7 +24,9 @@ Given a simple application in ``api.py``::
if __name__ == "__main__":
api.run()
You can test it with pytest::
You can test it with pytest. Every Responder ``API`` instance has a
``requests`` property that gives you a test client — use it exactly like
you'd use ``requests`` or ``httpx``::
# test_api.py
import api as service
@@ -35,12 +39,15 @@ Run your tests::
$ pytest
That's really all there is to it. No configuration, no test server setup.
Using Fixtures
--------------
For larger test suites, use pytest fixtures to share the API instance
across tests::
For larger test suites, pytest fixtures keep things organized. Create a
fixture that returns your API instance, and every test gets a fresh
reference to it::
import pytest
import api as service
@@ -62,13 +69,16 @@ across tests::
assert r.json() == {"key": "value"}
The ``api.url_for()`` method generates a URL for a given route endpoint,
so you don't have to hard-code paths in your tests.
so you don't have to hard-code paths in your tests. If you rename a route
later, your tests won't break.
Testing JSON APIs
-----------------
Send JSON data and check the response::
Most APIs send and receive JSON. The test client makes this natural — pass
``json=`` to send a JSON body, and call ``.json()`` on the response to
parse it::
def test_create_item(api):
@api.route("/items")
@@ -81,11 +91,45 @@ Send JSON data and check the response::
assert r.status_code == 201
assert r.json() == {"created": {"name": "widget"}}
You can also test content negotiation by setting the ``Accept`` header::
r = api.requests.get("/data", headers={"Accept": "application/x-yaml"})
assert "key: value" in r.text
Testing Request Validation
--------------------------
If you're using Pydantic models for request validation, you can test
that invalid inputs are properly rejected::
from pydantic import BaseModel
class Item(BaseModel):
name: str
price: float
def test_validation(api):
@api.route("/items", methods=["POST"], request_model=Item)
async def create(req, resp):
data = await req.media()
resp.media = data
# Valid request
r = api.requests.post("/items", json={"name": "thing", "price": 9.99})
assert r.status_code == 200
# Missing required field
r = api.requests.post("/items", json={"name": "thing"})
assert r.status_code == 422
assert "errors" in r.json()
Testing File Uploads
--------------------
Send files using the ``files`` parameter::
File uploads use the ``files`` parameter, just like the ``requests``
library. Each file is a tuple of ``(filename, content, content_type)``::
def test_upload(api):
@api.route("/upload")
@@ -98,10 +142,29 @@ Send files using the ``files`` parameter::
assert r.json() == {"received": ["doc"]}
Testing Headers and Cookies
----------------------------
Check response headers and cookies just like you would with any HTTP
client::
def test_headers(api):
@api.route("/")
def view(req, resp):
resp.headers["X-Custom"] = "hello"
resp.cookies["session"] = "abc123"
r = api.requests.get("/")
assert r.headers["X-Custom"] == "hello"
assert "session" in r.cookies
Testing WebSockets
------------------
Use Starlette's ``TestClient`` directly for WebSocket connections::
WebSocket tests use Starlette's ``TestClient`` directly, since WebSocket
connections require a different protocol. The ``websocket_connect`` context
manager gives you a connection you can send and receive on::
from starlette.testclient import TestClient
@@ -109,19 +172,23 @@ Use Starlette's ``TestClient`` directly for WebSocket connections::
@api.route("/ws", websocket=True)
async def ws(ws):
await ws.accept()
await ws.send_text("hello")
name = await ws.receive_text()
await ws.send_text(f"hello, {name}!")
await ws.close()
client = TestClient(api)
with client.websocket_connect("/ws") as ws:
assert ws.receive_text() == "hello"
ws.send_text("world")
assert ws.receive_text() == "hello, world!"
Testing Error Handling
----------------------
To test error responses without pytest raising the exception, disable
server exception propagation::
By default, the test client raises exceptions from your route handlers,
which is usually what you want — it makes bugs obvious. But when you're
testing error handling specifically, you want to see the error response
instead. Disable exception propagation with ``raise_server_exceptions``::
from starlette.testclient import TestClient
@@ -134,12 +201,30 @@ server exception propagation::
r = client.get(api.url_for(fail))
assert r.status_code == 500
If you've registered a custom exception handler, you can test that too::
def test_custom_error(api):
@api.exception_handler(ValueError)
async def handle(req, resp, exc):
resp.status_code = 400
resp.media = {"error": str(exc)}
@api.route("/fail")
def fail(req, resp):
raise ValueError("bad input")
client = TestClient(api, raise_server_exceptions=False)
r = client.get(api.url_for(fail))
assert r.status_code == 400
assert r.json() == {"error": "bad input"}
Testing Lifespan Events
-----------------------
The test client supports lifespan events. Use ``with`` to ensure startup
and shutdown hooks run::
If your app uses startup and shutdown events (for database connections,
caches, etc.), you need the test client to trigger them. Wrap the client
in a ``with`` block — startup runs on enter, shutdown runs on exit::
def test_with_lifespan(api):
started = {"value": False}
@@ -155,3 +240,101 @@ and shutdown hooks run::
with api.requests as session:
r = session.get("http://;/")
assert r.json() == {"started": True}
Without the ``with`` block, lifespan events won't fire, which can lead to
confusing test failures if your routes depend on startup initialization.
Testing Before and After Hooks
------------------------------
Before-request and after-request hooks run automatically during tests,
just like in production. You can verify their effects on the response::
def test_hooks(api):
@api.route(before_request=True)
def add_version(req, resp):
resp.headers["X-Version"] = "3.2"
@api.after_request()
def add_timing(req, resp):
resp.headers["X-Served-By"] = "responder"
@api.route("/")
def view(req, resp):
resp.text = "ok"
r = api.requests.get("/")
assert r.headers["X-Version"] == "3.2"
assert r.headers["X-Served-By"] == "responder"
Testing Rate Limiting
---------------------
Rate limiters are just hooks — they run automatically during tests.
Verify the headers and the 429 response::
from responder.ext.ratelimit import RateLimiter
def test_rate_limiting():
api = responder.API(allowed_hosts=["localhost"])
limiter = RateLimiter(requests=2, period=60)
limiter.install(api)
@api.route("/")
def view(req, resp):
resp.text = "ok"
# First two requests succeed
for _ in range(2):
r = api.requests.get("http://localhost/")
assert r.status_code == 200
assert "X-RateLimit-Remaining" in r.headers
# Third request is rate limited
r = api.requests.get("http://localhost/")
assert r.status_code == 429
Testing Mounted Apps
--------------------
When testing WSGI apps mounted at a subroute, use ``localhost`` as the
host to avoid Werkzeug's trusted host validation::
from flask import Flask
def test_flask_mount():
api = responder.API(allowed_hosts=["localhost"])
flask_app = Flask(__name__)
@flask_app.route("/")
def hello():
return "Hello from Flask!"
api.mount("/flask", flask_app)
r = api.requests.get("http://localhost/flask")
assert r.status_code == 200
assert "Hello from Flask" in r.text
Tips
----
- **Keep tests fast.** The in-process test client is already fast — no
network overhead. Avoid ``time.sleep()`` in tests.
- **One API per test** when testing configuration. If you need a specific
``API()`` configuration (like ``cors=True``), create a new instance
in the test rather than sharing the fixture.
- Use ``api.url_for()`` instead of hard-coded paths. It's a small
thing, but it makes refactoring painless.
- **Test the contract, not the implementation.** Assert on status codes,
response bodies, and headers — not on internal state.
- **Use ``localhost`` for mounted WSGI apps.** Werkzeug 3.1.7+ validates
the ``Host`` header, so avoid synthetic hosts like ``;`` in tests.
+406 -176
View File
@@ -1,15 +1,27 @@
Feature Tour
============
This section walks through Responder's features in detail. Each section
includes working code examples you can copy into your application.
This section walks through Responder's features in depth. Each section
explains the concept, shows working code, and explains the design choices
behind it. If you're new to web development, this is a good place to learn
how modern web frameworks work under the hood.
Method Filtering
----------------
By default, a route matches all HTTP methods. If you want to restrict a
route to specific methods, pass the ``methods`` parameter::
HTTP defines several *methods* (also called verbs) that describe what a
client wants to do with a resource. The most common are:
- ``GET`` — retrieve data
- ``POST`` — create something new
- ``PUT`` — replace something entirely
- ``PATCH`` — update part of something
- ``DELETE`` — remove something
By default, a Responder route matches all methods. This is fine for simple
endpoints, but REST APIs typically map different methods to different
operations. Use the ``methods`` parameter to restrict a route::
@api.route("/items", methods=["GET"])
def list_items(req, resp):
@@ -20,15 +32,22 @@ route to specific methods, pass the ``methods`` parameter::
data = await req.media()
resp.media = {"created": data}
Note the ``check_existing=False``this allows you to register multiple
handlers for the same path with different methods.
Note the ``check_existing=False``Responder normally prevents you from
registering two routes with the same path (to catch typos). When you
intentionally want multiple handlers for the same path with different
methods, you need to opt in.
Class-Based Views
-----------------
For more complex resources, you can use class-based views. Responder will
dispatch to the appropriate method handler based on the HTTP method::
Function-based views are great for simple endpoints, but sometimes you want
to group related HTTP methods together into a single resource. This is
where class-based views come in — a pattern popularized by
`Falcon <https://falconframework.org/>`_.
Responder dispatches to the appropriate method handler based on the HTTP
method::
@api.route("/{greeting}")
class GreetingResource:
@@ -47,14 +66,19 @@ middleware scoped to a single route. Method-specific handlers (``on_get``,
``on_post``, ``on_put``, ``on_delete``, etc.) are called after.
No inheritance required — just define a class with the right method names.
This is simpler than Django's ``View`` classes and more Pythonic than
framework-specific base classes.
Lifespan Events
---------------
Modern applications often need to set up resources on startup (database
connections, caches, ML models) and tear them down on shutdown. Responder
supports the lifespan context manager pattern::
Real applications need to set up resources when they start (database
connection pools, ML models, caches) and tear them down when they stop.
This is called the application *lifespan*.
The modern approach is the *context manager* pattern, where startup and
shutdown are two halves of the same block::
from contextlib import asynccontextmanager
@@ -68,7 +92,11 @@ supports the lifespan context manager pattern::
api = responder.API(lifespan=lifespan)
You can also use the traditional event decorator style::
Everything before ``yield`` runs at startup. Everything after runs at
shutdown. If startup fails, the server won't start. If shutdown raises,
it's logged but the server still exits.
The traditional event decorator style also works::
@api.on_event("startup")
async def startup():
@@ -78,57 +106,71 @@ You can also use the traditional event decorator style::
async def shutdown():
print("shutting down")
The context manager approach is preferred for new code — it makes the
startup/shutdown relationship explicit and keeps related code together.
The context manager is preferred for new code — it keeps related startup
and shutdown logic together and makes resource cleanup more explicit.
Serving Files
-------------
Serve files from disk with automatic content-type detection. Responder
uses Python's ``mimetypes`` module to figure out the right ``Content-Type``
header for you::
Web applications often need to serve files — downloads, reports, images.
Responder makes this simple with ``resp.file()``, which reads a file from
disk and sets the ``Content-Type`` header automatically using Python's
``mimetypes`` module::
@api.route("/download")
def download(req, resp):
resp.file("reports/annual.pdf")
You can override the content type if needed::
You can override the content type if the automatic detection isn't right::
@api.route("/image")
def image(req, resp):
resp.file("photos/cat.jpg", content_type="image/jpeg")
For large files, use ``resp.stream_file()`` to avoid loading the entire
file into memory. This streams the file in chunks::
@api.route("/export")
def export(req, resp):
resp.stream_file("data/export.csv")
Custom Error Handling
---------------------
By default, unhandled exceptions result in a 500 Internal Server Error.
You can register custom handlers for specific exception types to return
structured error responses::
In production, you don't want your users to see raw Python tracebacks.
Responder lets you register custom handlers for specific exception types,
so you can return clean, structured error responses::
@api.exception_handler(ValueError)
async def handle_value_error(req, resp, exc):
resp.status_code = 400
resp.media = {"error": str(exc)}
Now, any route that raises a ``ValueError`` will return a clean 400 response
with a JSON error message instead of a generic 500 page.
Now, any route that raises a ``ValueError`` will return a clean JSON
response with a 400 status code instead of a generic 500 error page.
This is a common pattern in API development — you define your own exception
classes for different error conditions, register handlers for each, and
your API always returns consistent, machine-readable error responses.
Before-Request Hooks
--------------------
Run code before every request. This is useful for logging, adding common
headers, or setting up per-request state::
Sometimes you need to run the same code before every request —
authentication checks, request logging, adding common headers, or setting
up per-request state. Before-request hooks let you do this without
duplicating code in every route::
@api.route(before_request=True)
def add_headers(req, resp):
resp.headers["X-API-Version"] = "3.1"
resp.headers["X-API-Version"] = "3.2"
**Short-circuiting:** If your hook sets ``resp.status_code``, the route
handler will be skipped entirely and the response will be sent immediately.
This is the pattern for authentication guards::
**Short-circuiting** is the really powerful part. If your hook sets
``resp.status_code``, the route handler is skipped entirely and the
response is sent immediately. This is the pattern for authentication::
@api.route(before_request=True)
def auth_check(req, resp):
@@ -137,19 +179,36 @@ This is the pattern for authentication guards::
resp.media = {"error": "unauthorized"}
If the ``Authorization`` header is missing, the client gets a 401 response
and the actual route handler never runs.
and the actual route handler never runs. This is cleaner than adding
auth checks to every individual route.
WebSocket hooks work the same way::
@api.before_request(websocket=True)
async def ws_auth(ws):
await ws.accept()
After-Request Hooks
-------------------
The complement to before-request hooks. After-request hooks run after the
route handler completes but before the response is sent. They're useful
for logging, adding response headers, or any post-processing::
@api.after_request()
def log_response(req, resp):
print(f"{req.method} {req.full_url} -> {resp.status_code}")
@api.after_request()
async def add_timing(req, resp):
resp.headers["X-Served-By"] = "responder"
WebSocket Support
-----------------
Responder supports WebSockets for real-time, bidirectional communication::
HTTP is a request-response protocol — the client asks, the server answers.
But some applications need real-time, bidirectional communication: chat
apps, live dashboards, multiplayer games, collaborative editors.
`WebSockets <https://en.wikipedia.org/wiki/WebSocket>`_ solve this by
upgrading an HTTP connection into a persistent, full-duplex channel where
both sides can send messages at any time::
@api.route("/ws", websocket=True)
async def websocket(ws):
@@ -161,14 +220,54 @@ Responder supports WebSockets for real-time, bidirectional communication::
You can send and receive in multiple formats:
- ``send_text`` / ``receive_text`` — plain text
- ``send_json`` / ``receive_json`` — JSON objects
- ``send_text`` / ``receive_text`` — plain text strings
- ``send_json`` / ``receive_json`` — JSON objects (auto-serialized)
- ``send_bytes`` / ``receive_bytes`` — raw binary data
WebSocket routes are marked with ``websocket=True`` in the route decorator.
They receive a ``ws`` object instead of ``req`` and ``resp``.
Server-Sent Events (SSE)
-------------------------
SSE is a simpler alternative to WebSockets for *one-way* real-time
communication — the server pushes events to the client, but the client
can't send messages back. This is perfect for live feeds, progress bars,
notification streams, and AI response streaming.
Unlike WebSockets, SSE works over plain HTTP, is automatically reconnected
by the browser, and doesn't require any special client-side libraries::
@api.route("/events")
async def events(req, resp):
@resp.sse
async def stream():
for i in range(10):
yield {"data": f"message {i}"}
On the client side, you consume SSE events with JavaScript's built-in
``EventSource`` API::
const source = new EventSource("/events");
source.onmessage = (event) => {
console.log(event.data);
};
Each yielded value can be a string (treated as data) or a dict with the
standard SSE fields::
yield {"event": "update", "data": "hello", "id": "1", "retry": "5000"}
yield "simple string message"
GraphQL
-------
`GraphQL <https://graphql.org/>`_ is a query language for APIs that lets
clients request exactly the data they need — no more, no less. Instead of
multiple REST endpoints, you define a schema and let clients query it.
Responder includes built-in GraphQL support via
`Graphene <https://graphene-python.org/>`_. Set up a full GraphQL endpoint
with a single method call::
@@ -183,9 +282,10 @@ with a single method call::
api.graphql("/graphql", schema=graphene.Schema(query=Query))
Visiting ``/graphql`` in a browser renders the GraphiQL interactive IDE,
where you can explore your schema and test queries. Programmatic clients
can POST JSON queries to the same endpoint.
Visiting ``/graphql`` in a browser renders the
`GraphiQL <https://github.com/graphql/graphiql>`_ interactive IDE, where
you can explore your schema, write queries, and see results in real-time.
Programmatic clients can POST JSON queries to the same endpoint.
You can access the Responder request and response objects in your resolvers
through ``info.context["request"]`` and ``info.context["response"]``.
@@ -194,8 +294,12 @@ through ``info.context["request"]`` and ``info.context["response"]``.
OpenAPI Documentation
---------------------
Responder can generate an OpenAPI schema and serve interactive API
documentation automatically::
`OpenAPI <https://www.openapis.org/>`_ (formerly Swagger) is the industry
standard for describing REST APIs. An OpenAPI specification lets you
auto-generate interactive documentation, client libraries, and validation
logic.
Responder generates OpenAPI specs from your code::
api = responder.API(
title="Pet Store",
@@ -211,9 +315,11 @@ This gives you:
There are three ways to document your endpoints.
**Pydantic models** — the recommended approach for new APIs. Use
``request_model`` and ``response_model`` to annotate your routes, and
Responder will generate the schema automatically::
**Pydantic models** — the recommended approach. Use ``request_model`` and
``response_model`` to annotate your routes, and Responder generates the
schema automatically. When ``request_model`` is set, request bodies are
also validated automatically — invalid inputs get a ``422`` response with
detailed error messages::
from pydantic import BaseModel
@@ -232,19 +338,11 @@ Responder will generate the schema automatically::
data = await req.media()
resp.media = {"id": 1, **data}
This generates a full OpenAPI path with ``requestBody`` and ``responses``
schemas, all linked by ``$ref`` to your Pydantic models in
``components/schemas``.
When ``response_model`` is set, the response is serialized through the
model — extra fields are stripped and types are enforced.
You can also register standalone schemas with the ``@api.schema`` decorator::
@api.schema("Pet")
class Pet(BaseModel):
name: str
age: int = 0
**YAML docstrings** — inline your OpenAPI spec directly in the docstring.
This gives you full control over every detail::
**YAML docstrings** — for full control, embed OpenAPI YAML in the
docstring::
@api.route("/pets")
def list_pets(req, resp):
@@ -258,8 +356,7 @@ This gives you full control over every detail::
"""
resp.media = [{"name": "Fido"}]
**Marshmallow schemas** — if you're already using marshmallow for
validation, Responder integrates with it via the apispec plugin::
**Marshmallow schemas** — if you're already using marshmallow::
from marshmallow import Schema, fields
@@ -267,19 +364,43 @@ validation, Responder integrates with it via the apispec plugin::
class PetSchema(Schema):
name = fields.Str()
All three approaches can be mixed in the same API. Pydantic models,
marshmallow schemas, and YAML docstrings all contribute to the same
generated OpenAPI specification.
All three approaches can be mixed in the same API. You can choose from
multiple documentation themes: ``swagger_ui`` (default), ``redoc``,
``rapidoc``, or ``elements``.
You can choose from multiple documentation themes:
``swagger_ui`` (default), ``redoc``, ``rapidoc``, or ``elements``.
Route Groups
------------
As your application grows, you'll want to organize routes logically.
Route groups let you share a URL prefix across related endpoints — a
common pattern for API versioning::
v1 = api.group("/v1")
@v1.route("/users")
def list_users(req, resp):
resp.media = []
@v1.route("/users/{user_id:int}")
def get_user(req, resp, *, user_id):
resp.media = {"id": user_id}
v2 = api.group("/v2")
@v2.route("/users")
def list_users_v2(req, resp):
resp.media = {"users": [], "total": 0}
This keeps your code organized without affecting the routing logic.
Mounting Other Apps
-------------------
Responder can mount any WSGI or ASGI application at a subroute. This means
you can gradually migrate from Flask, or run multiple frameworks side by side::
Responder can mount any WSGI or ASGI application at a subroute. This is
incredibly useful for gradual migrations — you can run Flask and Responder
side by side, moving routes over one at a time::
from flask import Flask
@@ -293,12 +414,33 @@ you can gradually migrate from Flask, or run multiple frameworks side by side::
Requests to ``/flask/`` will be handled by Flask. Everything else goes
through Responder. Both WSGI and ASGI apps are supported — Responder
wraps WSGI apps automatically.
wraps WSGI apps in an ASGI adapter automatically.
You can also mount `marimo <https://marimo.io/>`_ notebooks as
interactive dashboards within your API::
import marimo
server = (
marimo.create_asgi_app()
.with_app(path="", root="./notebooks/dashboard.py")
.with_app(path="/analysis", root="./notebooks/analysis.py")
)
api.mount("/notebooks", server.build())
Notebooks are served at ``/notebooks/`` and ``/notebooks/analysis``,
with full interactivity — reactive cells, widgets, plots, and all.
Cookies
-------
`Cookies <https://developer.mozilla.org/en-US/docs/Web/HTTP/Cookies>`_ are
small pieces of data that the server asks the browser to store and send
back with every subsequent request. They're the foundation of sessions,
authentication tokens, and user preferences on the web.
Reading and writing cookies is straightforward::
# Read cookies from the request
@@ -307,26 +449,28 @@ Reading and writing cookies is straightforward::
# Set a cookie on the response
resp.cookies["hello"] = "world"
For more control over cookie directives, use ``set_cookie``::
For production use, you'll want to set security directives. The
``httponly`` flag prevents JavaScript from reading the cookie (defending
against XSS attacks), and ``secure`` ensures it's only sent over HTTPS::
resp.set_cookie(
"token",
value="abc123",
max_age=3600,
secure=True,
httponly=True,
max_age=3600, # expires in 1 hour
secure=True, # HTTPS only
httponly=True, # no JavaScript access
path="/",
)
Supported directives: ``key``, ``value``, ``expires``, ``max_age``,
``domain``, ``path``, ``secure``, ``httponly``.
Cookie-Based Sessions
---------------------
Responder has built-in support for signed, cookie-based sessions. Just
read from and write to the ``session`` dictionary::
Sessions let you store per-user data across multiple requests. Responder's
built-in sessions are cookie-based — the session data is serialized, signed
with your secret key, and stored in a cookie. The signature prevents
tampering: if someone modifies the cookie, the signature won't match and
the data will be rejected::
@api.route("/login")
def login(req, resp):
@@ -336,13 +480,9 @@ read from and write to the ``session`` dictionary::
def profile(req, resp):
resp.media = {"user": req.session.get("username")}
The session data is stored in a cookie called ``Responder-Session``. It's
signed for tamper protection, so you can trust that the data originated
from your server.
.. warning::
For production use, always set a secret key::
Always set a secret key in production. The default key is not secret::
api = responder.API(secret_key="your-secret-key-here")
@@ -350,141 +490,98 @@ from your server.
Static Files
------------
Static files are served from the ``static/`` directory by default::
Most web applications serve static assets — CSS stylesheets, JavaScript
files, images, fonts. Responder serves these from the ``static/`` directory
by default::
api = responder.API(static_dir="static", static_route="/static")
Place your CSS, JavaScript, images, and other assets in the ``static/``
directory and they'll be served automatically.
Place your assets in the ``static/`` directory and they'll be served
automatically at ``/static/style.css``, ``/static/app.js``, etc.
For single-page applications, you can serve ``index.html`` as the default
response for all unmatched routes::
For single-page applications (React, Vue, Angular), you can serve
``index.html`` as the default response for all unmatched routes::
api.add_route("/", static=True)
You can add additional static directories at runtime::
api.static_app.add_directory("extra_assets")
CORS
----
Enable Cross-Origin Resource Sharing for your API::
`CORS <https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS>`_ (Cross-
Origin Resource Sharing) is a security mechanism that controls which
websites can make requests to your API. Browsers enforce this — if your
API is at ``api.example.com`` and your frontend is at ``app.example.com``,
the browser will block requests unless your API explicitly allows it.
Enable CORS and configure which origins are allowed::
api = responder.API(cors=True, cors_params={
"allow_origins": ["https://example.com"],
"allow_origins": ["https://app.example.com"],
"allow_methods": ["GET", "POST"],
"allow_headers": ["*"],
"allow_credentials": True,
"max_age": 600,
})
The default CORS policy is restrictive — you must explicitly enable the
origins, methods, and headers your frontend needs.
The default policy is restrictive — you must explicitly allow each origin.
Using ``["*"]`` for allow_origins permits any website to call your API,
which is fine for public APIs but not for private ones.
HSTS
----
Force all traffic to HTTPS with a single flag::
`HSTS <https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Strict-Transport-Security>`_
(HTTP Strict Transport Security) tells browsers to always use HTTPS when
communicating with your server. Once a browser sees the HSTS header, it
will refuse to connect over plain HTTP, even if the user types ``http://``
in the address bar::
api = responder.API(enable_hsts=True)
This adds the ``Strict-Transport-Security`` header and redirects HTTP
requests to HTTPS.
Trusted Hosts
-------------
Protect against HTTP Host header attacks by restricting which hostnames
your application will respond to::
The ``Host`` header in an HTTP request tells the server which domain name
the client used. Attackers can forge this header to trick your application
into generating URLs to malicious domains (a class of attack called *Host
header injection*).
Restrict which hostnames your application accepts::
api = responder.API(allowed_hosts=["example.com", "*.example.com"])
Requests with a ``Host`` header that doesn't match any of the patterns
will receive a 400 Bad Request response. Wildcard domains are supported.
By default, all hostnames are allowed.
Server-Sent Events (SSE)
------------------------
Stream real-time updates to the client using Server-Sent Events. This is
great for live feeds, progress updates, and AI streaming responses::
@api.route("/events")
async def events(req, resp):
@resp.sse
async def stream():
for i in range(10):
yield {"data": f"message {i}"}
Each yielded value can be a string (treated as data) or a dict with
``data``, ``event``, ``id``, and ``retry`` fields::
yield {"event": "update", "data": "hello", "id": "1"}
yield "simple string message"
Streaming Files
---------------
For large files, use ``resp.stream_file()`` to stream the content without
loading the entire file into memory::
@api.route("/download")
def download(req, resp):
resp.stream_file("large-dataset.csv")
For small files where memory isn't a concern, ``resp.file()`` loads the
entire file at once — simpler but less efficient for large files.
After-Request Hooks
-------------------
Run code after every request, useful for logging, adding headers, or
cleanup::
@api.after_request()
def log_response(req, resp):
print(f"{req.method} {req.full_url} -> {resp.status_code}")
Route Groups
------------
Organize related routes with a shared URL prefix. Useful for API versioning
and logical grouping::
v1 = api.group("/v1")
@v1.route("/users")
def list_users(req, resp):
resp.media = []
@v1.route("/users/{user_id:int}")
def get_user(req, resp, *, user_id):
resp.media = {"id": user_id}
Requests with unrecognized hosts get a ``400 Bad Request``. Wildcard
patterns are supported. By default, all hostnames are allowed.
Request ID
----------
Auto-generate unique request IDs for tracing and debugging. If the client
sends an ``X-Request-ID`` header, it's forwarded; otherwise a new UUID is
generated::
In distributed systems, tracing a single request across multiple services
is essential for debugging. Request IDs are unique identifiers attached to
each request — if something goes wrong, you can search your logs for that
ID and find every related event.
Responder can auto-generate request IDs. If the client sends an
``X-Request-ID`` header (common in microservice architectures), it's
forwarded. Otherwise, a new UUID is generated::
api = responder.API(request_id=True)
The ID appears in the ``X-Request-ID`` response header.
Rate Limiting
-------------
Built-in token bucket rate limiter::
Rate limiting prevents individual clients from overwhelming your API with
too many requests. It's essential for public APIs, and good practice even
for internal ones.
Responder includes a built-in token bucket rate limiter::
from responder.ext.ratelimit import RateLimiter
@@ -492,17 +589,150 @@ Built-in token bucket rate limiter::
limiter.install(api)
When the limit is exceeded, clients receive a ``429 Too Many Requests``
response with ``Retry-After`` and ``X-RateLimit-Remaining`` headers.
response with a ``Retry-After`` header. Every response includes
``X-RateLimit-Limit`` and ``X-RateLimit-Remaining`` headers so clients
can pace themselves.
The rate limiter is per-client, keyed by IP address.
Structured Logging
------------------
Production applications need structured, searchable logs. Responder
includes built-in logging that automatically attaches request context
— request ID, HTTP method, path, and client IP — to every log message
emitted during request handling::
api = responder.API(enable_logging=True)
This gives you:
- **Access logging** with timing for every request::
2026-03-24 12:00:00 [INFO] responder.access — GET /users → 200 (1.2ms)
- **A logger on the API instance** — use ``api.log`` anywhere in
your routes. Request context (ID, method, path, client IP) is
attached automatically::
@api.route("/users/{user_id:int}")
def get_user(req, resp, *, user_id):
api.log.info("fetching user %d", user_id)
# => [INFO] responder.app -- fetching user 42 [GET /users/42] [req:a1b2c3] [client:10.0.0.1]
resp.media = {"id": user_id}
- **Request IDs** generated automatically (or forwarded from the
``X-Request-ID`` header) and included in responses.
The logging uses Python's standard ``logging`` module, so it works with
any handler — files, syslog, JSON formatters, Datadog, Sentry, whatever
you already use.
For additional loggers (e.g. in helper modules), use ``get_logger``::
from responder.ext.logging import get_logger
logger = get_logger("myapp.db")
You can also access the current request context directly::
from responder.ext.logging import RequestContext
@api.route("/debug")
def debug(req, resp):
resp.media = {
"request_id": RequestContext.get_request_id(),
"client_ip": RequestContext.get_client_ip(),
}
When ``enable_logging=True`` is set, it supersedes ``request_id=True``
— the logging middleware handles request IDs itself, so you don't get
duplicate headers.
Pydantic Validation
-------------------
`Pydantic <https://docs.pydantic.dev/>`_ models integrate directly with
Responder's routing. Set ``request_model`` to validate incoming data and
``response_model`` to control the shape of outgoing data::
from pydantic import BaseModel
class ItemIn(BaseModel):
name: str
price: float
class ItemOut(BaseModel):
id: int
name: str
price: float
@api.route("/items", methods=["POST"],
request_model=ItemIn, response_model=ItemOut)
async def create_item(req, resp):
data = await req.media()
resp.media = {"id": 1, **data}
When ``request_model`` is set:
- Valid requests are parsed and the data is available via ``await req.media()``
- Invalid requests get an automatic ``422 Unprocessable Entity`` response
with detailed error messages — you don't write any validation code
When ``response_model`` is set:
- The response is serialized through the model before being sent
- Extra fields are stripped automatically
- Type coercion happens at the boundary
This is the recommended way to build validated REST APIs with Responder.
See the :doc:`tutorial-rest` for a complete walkthrough.
Content Negotiation
-------------------
Responder automatically negotiates the response format based on the
client's ``Accept`` header. Set ``resp.media`` to a Python object and
the right thing happens:
- ``Accept: application/json`` (default) → JSON
- ``Accept: application/x-yaml`` → YAML
- ``Accept: application/x-msgpack`` → MessagePack
This means a single endpoint serves multiple formats without any
conditional logic in your code::
@api.route("/data")
def data(req, resp):
resp.media = {"key": "value"}
Clients get the format they ask for::
$ curl http://localhost:5042/data
{"key": "value"}
$ curl -H "Accept: application/x-yaml" http://localhost:5042/data
key: value
MessagePack
-----------
In addition to JSON and YAML, Responder supports MessagePack for efficient
binary serialization::
`MessagePack <https://msgpack.org/>`_ is a binary serialization format
that's more compact and faster to parse than JSON. It's useful for
high-throughput APIs, IoT devices, and anywhere bandwidth matters.
# Decode MessagePack request body
Responder supports MessagePack alongside JSON and YAML::
# Decode a MessagePack request body
data = await req.media("msgpack")
# Content negotiation also works — clients can send
# Accept: application/x-msgpack to receive MessagePack responses.
# Respond with MessagePack
resp.media = {"result": [1, 2, 3]}
Content negotiation works automatically — clients can send
``Accept: application/x-msgpack`` to receive MessagePack responses
instead of JSON. You can also explicitly decode MessagePack request
bodies by passing ``"msgpack"`` to ``req.media()``.
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Authentication
==============
Every API that handles user data needs authentication — a way to verify
who is making a request. This guide covers the most common patterns:
API keys, JWT tokens, and how to build reusable auth guards with
Responder's before-request hooks.
API Key Authentication
----------------------
The simplest approach. The client sends a secret key in a header, and
your server checks it against a known value. This is common for
server-to-server communication and simple APIs::
API_KEYS = {"sk-abc123", "sk-def456"}
@api.route(before_request=True)
def check_api_key(req, resp):
key = req.headers.get("X-API-Key")
if key not in API_KEYS:
resp.status_code = 401
resp.media = {"error": "Invalid or missing API key"}
Because the before-request hook sets ``resp.status_code``, the route
handler is skipped entirely for unauthorized requests. The client never
reaches your endpoint — the guard catches them first.
The client sends the key like this::
$ curl -H "X-API-Key: sk-abc123" http://localhost:5042/protected
Bearer Token Authentication
----------------------------
Bearer tokens are the standard for modern APIs. The client sends a token
in the ``Authorization`` header, and the server validates it. The most
common format is `JWT <https://jwt.io/>`_ (JSON Web Tokens).
Install PyJWT::
$ uv pip install pyjwt
Create a helper to encode and decode tokens::
import jwt
from datetime import datetime, timedelta, timezone
SECRET = "your-secret-key"
def create_token(user_id: int) -> str:
payload = {
"sub": user_id,
"exp": datetime.now(timezone.utc) + timedelta(hours=24),
}
return jwt.encode(payload, SECRET, algorithm="HS256")
def verify_token(token: str) -> dict | None:
try:
return jwt.decode(token, SECRET, algorithms=["HS256"])
except jwt.InvalidTokenError:
return None
Add a login endpoint that issues tokens, and a before-request hook that
verifies them::
@api.route("/login", methods=["POST"])
async def login(req, resp):
data = await req.media()
# In a real app, check credentials against a database
if data.get("username") == "admin" and data.get("password") == "secret":
token = create_token(user_id=1)
resp.media = {"token": token}
else:
resp.status_code = 401
resp.media = {"error": "Invalid credentials"}
@api.route(before_request=True)
def auth_guard(req, resp):
# Skip auth for the login endpoint itself
if req.url.path == "/login":
return
auth = req.headers.get("Authorization", "")
if not auth.startswith("Bearer "):
resp.status_code = 401
resp.media = {"error": "Missing bearer token"}
return
token = auth[7:] # Strip "Bearer "
payload = verify_token(token)
if payload is None:
resp.status_code = 401
resp.media = {"error": "Invalid or expired token"}
return
# Store the authenticated user on the request state
req.state.user_id = payload["sub"]
Now any route can access the authenticated user::
@api.route("/me")
def get_me(req, resp):
resp.media = {"user_id": req.state.user_id}
The client flow:
1. ``POST /login`` with credentials → receive a token
2. Include ``Authorization: Bearer <token>`` on every subsequent request
3. The token expires after 24 hours — the client must log in again
Skipping Auth for Public Routes
--------------------------------
The example above skips auth for ``/login`` by checking the path. For
more control, you can use a set of public paths::
PUBLIC_PATHS = {"/login", "/signup", "/health", "/docs", "/schema.yml"}
@api.route(before_request=True)
def auth_guard(req, resp):
if req.url.path in PUBLIC_PATHS:
return
# ... check token
Custom Exception for Auth Errors
---------------------------------
For cleaner code, define a custom exception and register a handler::
class AuthError(Exception):
def __init__(self, message="Unauthorized", status_code=401):
self.message = message
self.status_code = status_code
@api.exception_handler(AuthError)
async def handle_auth_error(req, resp, exc):
resp.status_code = exc.status_code
resp.media = {"error": exc.message}
Now your auth guard can simply raise::
@api.route(before_request=True)
def auth_guard(req, resp):
if req.url.path in PUBLIC_PATHS:
return
if "Authorization" not in req.headers:
raise AuthError("Missing authorization header")
Using Sessions for Web Apps
----------------------------
For traditional web applications (with HTML pages and forms), cookie-based
sessions are simpler than tokens. The browser handles cookies automatically
— no client-side token management needed::
@api.route("/login", methods=["POST"])
async def login(req, resp):
data = await req.media("form")
if data["username"] == "admin" and data["password"] == "secret":
resp.session["user"] = data["username"]
api.redirect(resp, location="/dashboard")
else:
resp.status_code = 401
resp.html = "<p>Invalid credentials</p>"
@api.route("/dashboard")
def dashboard(req, resp):
user = req.session.get("user")
if not user:
api.redirect(resp, location="/login")
return
resp.html = f"<h1>Welcome, {user}!</h1>"
@api.route("/logout")
def logout(req, resp):
resp.session.clear()
api.redirect(resp, location="/login")
Remember to set a proper secret key::
api = responder.API(secret_key="your-production-secret-key")
The session data is signed (not encrypted) — users can read it but
can't tamper with it. Don't store sensitive data like passwords in
sessions.
Role-Based Access Control
--------------------------
For APIs where different users have different permissions, embed the
role in the token and check it in route-specific guards::
def create_token(user_id: int, role: str = "user") -> str:
payload = {
"sub": user_id,
"role": role,
"exp": datetime.now(timezone.utc) + timedelta(hours=24),
}
return jwt.encode(payload, SECRET, algorithm="HS256")
Create a helper that checks for a specific role::
def require_role(*roles):
"""Before-request hook factory that restricts by role."""
def check(req, resp):
user_role = getattr(req.state, "role", None)
if user_role not in roles:
resp.status_code = 403
resp.media = {"error": "Insufficient permissions"}
return check
Use it on specific routes::
@api.route("/admin/users", before_request=require_role("admin"))
def list_all_users(req, resp):
resp.media = {"users": [...]}
And store the role during token verification::
# In your auth_guard:
req.state.user_id = payload["sub"]
req.state.role = payload.get("role", "user")
Choosing an Auth Strategy
--------------------------
- **API keys** — simplest. Good for server-to-server, CLI tools, and
internal services. No expiration unless you build it.
- **JWT tokens** — standard for SPAs and mobile apps. Stateless, so
they scale well. Downside: you can't revoke them without a blocklist.
- **Sessions** — best for traditional web apps with HTML forms. The
browser manages cookies automatically. Stateful — the server controls
the session lifecycle.
Start with API keys for internal tools, JWT for public APIs, and
sessions for web apps with login pages.
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Migrating from Flask
====================
If you're coming from Flask, you'll find Responder familiar but different
in a few key ways. This guide maps Flask concepts to their Responder
equivalents and shows you how to translate common patterns.
The Big Differences
-------------------
**No return values.** In Flask, you return a response. In Responder, you
mutate it. This is the single biggest difference:
Flask::
@app.route("/")
def hello():
return "hello, world!"
Responder::
@api.route("/")
def hello(req, resp):
resp.text = "hello, world!"
**Explicit request and response.** Flask uses a global ``request`` object
(via thread-local magic). Responder passes ``req`` and ``resp`` explicitly.
No magic, no import needed — they're right there in the function signature.
**ASGI, not WSGI.** Flask runs on WSGI, which is synchronous. Responder
runs on ASGI, which supports async natively. You can still write sync
views — Responder runs them in a thread pool automatically.
Quick Reference
---------------
.. list-table::
:header-rows: 1
:widths: 40 60
* - Flask
- Responder
* - ``Flask(__name__)``
- ``responder.API()``
* - ``return "text"``
- ``resp.text = "text"``
* - ``return jsonify(data)``
- ``resp.media = data``
* - ``return render_template("t.html", x=1)``
- ``resp.html = api.template("t.html", x=1)``
* - ``request.args["q"]``
- ``req.params["q"]``
* - ``request.json``
- ``await req.media()``
* - ``request.form``
- ``await req.media("form")``
* - ``request.headers["X"]``
- ``req.headers["X"]``
* - ``request.method``
- ``req.method``
* - ``request.cookies["x"]``
- ``req.cookies["x"]``
* - ``session["x"] = 1``
- ``resp.session["x"] = 1``
* - ``abort(404)``
- ``resp.status_code = 404``
* - ``redirect("/new")``
- ``api.redirect(resp, location="/new")``
* - ``@app.before_request``
- ``@api.route(before_request=True)``
* - ``@app.errorhandler(404)``
- ``@api.exception_handler(ValueError)``
* - ``app.run(debug=True)``
- ``api.run(debug=True)``
Route Parameters
----------------
Flask uses ``<angle_brackets>``. Responder uses ``{curly_braces}``
with the same type convertor idea:
Flask::
@app.route("/users/<int:user_id>")
def get_user(user_id):
return jsonify({"id": user_id})
Responder::
@api.route("/users/{user_id:int}")
def get_user(req, resp, *, user_id):
resp.media = {"id": user_id}
Note the ``*`` — route parameters are keyword-only arguments in
Responder. This makes the interface explicit about which arguments
come from the URL.
JSON APIs
---------
Flask::
@app.route("/api/items", methods=["POST"])
def create_item():
data = request.json
# ... create item
return jsonify(item), 201
Responder::
@api.route("/api/items", methods=["POST"])
async def create_item(req, resp):
data = await req.media()
# ... create item
resp.media = item
resp.status_code = 201
The ``await`` is needed because reading the request body is an async
I/O operation. This is more explicit than Flask's approach, and it
means the event loop isn't blocked while waiting for the body to arrive.
Templates
---------
Both use Jinja2. The syntax is nearly identical:
Flask::
@app.route("/hello/<name>")
def hello(name):
return render_template("hello.html", name=name)
Responder::
@api.route("/hello/{name}")
def hello(req, resp, *, name):
resp.html = api.template("hello.html", name=name)
Blueprints → Route Groups
--------------------------
Flask uses Blueprints to organize routes. Responder has route groups:
Flask::
bp = Blueprint("api", __name__, url_prefix="/api")
@bp.route("/users")
def list_users():
return jsonify([])
app.register_blueprint(bp)
Responder::
api_v1 = api.group("/api")
@api_v1.route("/users")
def list_users(req, resp):
resp.media = []
Gradual Migration
-----------------
You don't have to migrate all at once. Responder can mount your existing
Flask app at a subroute, so you can move endpoints over one at a time::
from flask import Flask
flask_app = Flask(__name__)
# Your existing Flask routes stay here
@flask_app.route("/legacy")
def legacy():
return "old endpoint"
# Mount Flask under /old, new routes go on Responder
api.mount("/old", flask_app)
@api.route("/new")
def new_endpoint(req, resp):
resp.media = {"modern": True}
Requests to ``/old/legacy`` go to Flask. Everything else goes to
Responder. When you've moved everything over, remove the mount.
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Writing Middleware
==================
Middleware sits between the server and your route handlers, processing
every request and response that flows through your application. It's the
right tool for cross-cutting concerns — things that apply to *all*
requests, not just specific routes.
Common middleware use cases:
- Request logging and timing
- Authentication and authorization
- Adding security headers
- Request ID generation
- Rate limiting
- Response compression (built-in)
Hooks vs. Middleware
--------------------
Responder gives you two levels of request processing:
**Hooks** (``before_request`` / ``after_request``) run inside Responder's
routing layer. They receive Responder's ``req`` and ``resp`` objects and
are the simplest way to add behavior::
@api.route(before_request=True)
def add_header(req, resp):
resp.headers["X-Powered-By"] = "Responder"
@api.after_request()
def log_request(req, resp):
print(f"{req.method} {req.url.path} -> {resp.status_code}")
**Middleware** runs at the ASGI level, wrapping the entire application.
It's more powerful but more complex — you work with raw ASGI scopes
instead of Responder objects. Use middleware when you need to process
requests *before* they reach Responder's routing, or when you need to
integrate with Starlette middleware.
Using Starlette Middleware
--------------------------
Responder is built on Starlette, so any Starlette middleware works
out of the box::
from starlette.middleware.base import BaseHTTPMiddleware
class TimingMiddleware(BaseHTTPMiddleware):
async def dispatch(self, request, call_next):
import time
start = time.time()
response = await call_next(request)
duration = time.time() - start
response.headers["X-Response-Time"] = f"{duration:.3f}s"
return response
api.add_middleware(TimingMiddleware)
The ``dispatch`` method receives a Starlette ``Request`` and a
``call_next`` function. Call ``call_next(request)`` to pass the request
to the next middleware (or to your route handler). The return value is
a Starlette ``Response`` that you can modify before it's sent.
Built-in Middleware
-------------------
Responder configures several middleware components automatically:
- **GZipMiddleware** — compresses responses larger than 500 bytes
- **TrustedHostMiddleware** — validates the ``Host`` header
- **ServerErrorMiddleware** — catches unhandled exceptions
- **ExceptionMiddleware** — routes exceptions to your handlers
- **SessionMiddleware** — manages signed cookie sessions
Optional middleware you can enable:
- **CORSMiddleware**``api = responder.API(cors=True)``
- **HTTPSRedirectMiddleware**``api = responder.API(enable_hsts=True)``
Adding Third-Party Middleware
-----------------------------
Any ASGI middleware can be added with ``api.add_middleware()``::
from some_package import SomeMiddleware
api.add_middleware(SomeMiddleware, option1="value", option2=True)
Keyword arguments are passed to the middleware's constructor.
Middleware Order
----------------
Middleware wraps your application like layers of an onion. The *last*
middleware added is the *outermost* layer — it sees the request first
and the response last.
Responder's built-in middleware stack (from outermost to innermost):
1. SessionMiddleware
2. ServerErrorMiddleware
3. CORSMiddleware (if enabled)
4. TrustedHostMiddleware
5. HTTPSRedirectMiddleware (if enabled)
6. GZipMiddleware
7. ExceptionMiddleware
8. Your routes
When you call ``api.add_middleware()``, your middleware is added *outside*
the existing stack. Keep this in mind for ordering dependencies — if
middleware A depends on middleware B having run first, add B before A.
Writing Pure ASGI Middleware
----------------------------
For maximum performance and control, you can write middleware as a plain
ASGI application. This bypasses Starlette's ``BaseHTTPMiddleware``
abstraction — it's faster and gives you direct access to the ASGI
protocol::
class SecurityHeadersMiddleware:
def __init__(self, app):
self.app = app
async def __call__(self, scope, receive, send):
if scope["type"] != "http":
await self.app(scope, receive, send)
return
async def send_with_headers(message):
if message["type"] == "http.response.start":
extra = [
(b"x-content-type-options", b"nosniff"),
(b"x-frame-options", b"DENY"),
(b"referrer-policy", b"strict-origin-when-cross-origin"),
]
message["headers"] = list(message["headers"]) + extra
await send(message)
await self.app(scope, receive, send_with_headers)
api.add_middleware(SecurityHeadersMiddleware)
This is the same pattern used internally by Starlette and uvicorn. The
middleware receives the ASGI ``scope``, ``receive``, and ``send`` callables,
and wraps ``send`` to inject headers into the response.
For most cases, ``BaseHTTPMiddleware`` is simpler and perfectly fine.
Use the pure ASGI approach when you need to handle WebSocket connections,
streaming responses, or want to avoid the overhead of request/response
object creation.
When to Use What
-----------------
- **Simple header additions, logging, auth checks** → use hooks
- **Response transformation, timing, third-party integrations** → use middleware
- **Rate limiting** → use the built-in ``RateLimiter`` (it uses hooks internally)
- **Request ID** → use ``api = responder.API(request_id=True)``
Start with hooks. They're simpler and cover most cases. Graduate to
middleware when hooks aren't enough.
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Building a REST API
===================
This tutorial walks you through building a complete REST API from scratch.
By the end, you'll have a working API with CRUD operations, request
validation, error handling, and interactive documentation.
We'll build a simple book catalog — a service that lets you create, read,
update, and delete books.
Project Setup
-------------
Create a new file called ``app.py``::
import responder
api = responder.API(
title="Book Catalog",
version="1.0",
openapi="3.0.2",
docs_route="/docs",
)
We're enabling OpenAPI documentation from the start. Visit ``/docs`` at
any point to see interactive Swagger UI for your API.
Define Your Models
------------------
We'll use `Pydantic <https://docs.pydantic.dev/>`_ to define our data
models. Pydantic models serve double duty — they validate incoming data
*and* generate OpenAPI schemas automatically::
from pydantic import BaseModel
class BookIn(BaseModel):
"""What the client sends when creating a book."""
title: str
author: str
year: int
isbn: str | None = None
class Book(BaseModel):
"""What the API returns."""
id: int
title: str
author: str
year: int
isbn: str | None = None
``BookIn`` is the *input* model — it doesn't have an ``id`` because the
server assigns that. ``Book`` is the *output* model — it includes
everything. This input/output separation is a common REST API pattern.
In-Memory Storage
-----------------
For this tutorial, we'll store books in a simple dict. In a real
application, you'd use a database (see :doc:`tutorial-sqlalchemy`)::
books_db: dict[int, dict] = {}
next_id = 1
List All Books
--------------
The first endpoint — list all books. This is a ``GET`` request to
``/books``::
@api.route("/books", methods=["GET"], response_model=list)
def list_books(req, resp):
resp.media = list(books_db.values())
In REST API design, ``GET`` requests should never modify data. They're
*safe* and *idempotent* — calling them multiple times has the same effect
as calling them once.
Create a Book
-------------
To create a book, the client sends a ``POST`` request with a JSON body.
We use ``request_model=BookIn`` to validate the input automatically — if
the client sends bad data, they get a ``422`` response with error details::
@api.route("/books", methods=["POST"], check_existing=False,
request_model=BookIn, response_model=Book)
async def create_book(req, resp):
global next_id
data = await req.media()
book = {"id": next_id, **data}
books_db[next_id] = book
next_id += 1
resp.media = book
resp.status_code = 201
Note ``resp.status_code = 201`` — the HTTP ``201 Created`` status code
tells the client that a new resource was successfully created. This is
more informative than a generic ``200 OK``.
Get a Single Book
-----------------
Retrieve a specific book by its ID. The ``{book_id:int}`` route parameter
ensures only integer IDs match — requests like ``/books/abc`` will 404::
@api.route("/books/{book_id:int}", methods=["GET"], response_model=Book)
def get_book(req, resp, *, book_id):
if book_id not in books_db:
resp.status_code = 404
resp.media = {"error": f"Book {book_id} not found"}
return
resp.media = books_db[book_id]
Update a Book
-------------
``PUT`` replaces a resource entirely. The client must send all fields::
@api.route("/books/{book_id:int}", methods=["PUT"], check_existing=False,
request_model=BookIn, response_model=Book)
async def update_book(req, resp, *, book_id):
if book_id not in books_db:
resp.status_code = 404
resp.media = {"error": f"Book {book_id} not found"}
return
data = await req.media()
book = {"id": book_id, **data}
books_db[book_id] = book
resp.media = book
Delete a Book
-------------
``DELETE`` removes a resource. The convention is to return ``204 No Content``
with an empty body on success::
@api.route("/books/{book_id:int}", methods=["DELETE"], check_existing=False)
def delete_book(req, resp, *, book_id):
if book_id not in books_db:
resp.status_code = 404
resp.media = {"error": f"Book {book_id} not found"}
return
del books_db[book_id]
resp.status_code = 204
Error Handling
--------------
Let's add a custom error handler so any ``ValueError`` in our code returns
a clean JSON response instead of a 500 error::
@api.exception_handler(ValueError)
async def handle_value_error(req, resp, exc):
resp.status_code = 400
resp.media = {"error": str(exc)}
Run It
------
Add the standard entry point at the bottom of your file::
if __name__ == "__main__":
api.run()
Start the server::
$ python app.py
Visit ``http://localhost:5042/docs`` to see your interactive API
documentation. You can test every endpoint directly from the browser.
Try It Out
----------
Using ``curl``::
# Create a book
$ curl -X POST http://localhost:5042/books \
-H "Content-Type: application/json" \
-d '{"title": "Dune", "author": "Frank Herbert", "year": 1965}'
# List all books
$ curl http://localhost:5042/books
# Get a specific book
$ curl http://localhost:5042/books/1
# Update a book
$ curl -X PUT http://localhost:5042/books/1 \
-H "Content-Type: application/json" \
-d '{"title": "Dune", "author": "Frank Herbert", "year": 1965, "isbn": "978-0441172719"}'
# Delete a book
$ curl -X DELETE http://localhost:5042/books/1
What's Next
-----------
This tutorial used in-memory storage. For a real application, you'll want
a database. See :doc:`tutorial-sqlalchemy` for how to integrate SQLAlchemy
with Responder using the lifespan pattern.
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Using SQLAlchemy
================
Most real web applications need a database. This guide shows how to
integrate `SQLAlchemy <https://www.sqlalchemy.org/>`_ with Responder,
using async support and the lifespan pattern for connection management.
SQLAlchemy is the most popular Python database toolkit. It gives you an
ORM (Object-Relational Mapper) for working with databases using Python
classes instead of raw SQL, plus a powerful query builder for when you
need fine-grained control.
Installation
------------
Install SQLAlchemy with async support and an async database driver.
We'll use SQLite for simplicity, but the pattern works with PostgreSQL,
MySQL, and any other database SQLAlchemy supports::
$ uv pip install 'sqlalchemy[asyncio]' aiosqlite
Define Your Models
------------------
SQLAlchemy models map Python classes to database tables. Each attribute
becomes a column::
# models.py
from sqlalchemy import String
from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column
class Base(DeclarativeBase):
pass
class Book(Base):
__tablename__ = "books"
id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
title: Mapped[str] = mapped_column(String, nullable=False)
author: Mapped[str] = mapped_column(String, nullable=False)
year: Mapped[int] = mapped_column(nullable=False)
isbn: Mapped[str | None] = mapped_column(String, nullable=True)
This uses SQLAlchemy 2.0's ``Mapped`` type annotations and
``mapped_column()``, which give you type checker support and cleaner
syntax than the older ``Column()`` style. Each model class corresponds
to a table, and each ``mapped_column()`` corresponds to a column.
Database Setup
--------------
Create the async engine and session factory. The *engine* manages
the connection pool. The *session* is your unit of work — you use it to
query and modify data within a transaction::
# database.py
from sqlalchemy.ext.asyncio import create_async_engine, async_sessionmaker
DATABASE_URL = "sqlite+aiosqlite:///./books.db"
engine = create_async_engine(DATABASE_URL, echo=True)
async_session = async_sessionmaker(engine, expire_on_commit=False)
The ``echo=True`` flag prints all SQL queries to the console — very
helpful during development, but you'll want to disable it in production.
The ``expire_on_commit=False`` flag keeps model attributes accessible
after a commit, which is convenient for returning created objects in
API responses.
Lifespan for Startup and Shutdown
----------------------------------
Use Responder's lifespan context manager to create the database tables
on startup and dispose of connections on shutdown::
# app.py
from contextlib import asynccontextmanager
import responder
from database import engine
from models import Base
@asynccontextmanager
async def lifespan(app):
# Startup: create tables
async with engine.begin() as conn:
await conn.run_sync(Base.metadata.create_all)
yield
# Shutdown: close all connections
await engine.dispose()
api = responder.API(lifespan=lifespan)
This is the proper way to manage database connections in an async
application. The lifespan context manager ensures that:
1. Tables are created before the first request
2. The connection pool is properly closed when the server shuts down
3. If table creation fails, the server won't start
CRUD Endpoints
--------------
Now let's build the API endpoints. Each one opens a database session,
does its work, and commits or rolls back::
from pydantic import BaseModel
from sqlalchemy import select
from database import async_session
from models import Book
# Pydantic models for request/response validation
class BookIn(BaseModel):
title: str
author: str
year: int
isbn: str | None = None
class BookOut(BaseModel):
id: int
title: str
author: str
year: int
isbn: str | None = None
class Config:
from_attributes = True
The ``from_attributes = True`` config tells Pydantic to read data from
SQLAlchemy model attributes (not just dicts). This lets you pass a
SQLAlchemy ``Book`` object directly to ``BookOut``.
**List all books**::
@api.route("/books", methods=["GET"])
async def list_books(req, resp):
async with async_session() as session:
result = await session.execute(select(Book))
books = result.scalars().all()
resp.media = [BookOut.model_validate(b).model_dump() for b in books]
**Create a book**::
@api.route("/books", methods=["POST"], check_existing=False,
request_model=BookIn, response_model=BookOut)
async def create_book(req, resp):
data = await req.media()
async with async_session() as session:
book = Book(**data)
session.add(book)
await session.commit()
await session.refresh(book)
resp.media = BookOut.model_validate(book).model_dump()
resp.status_code = 201
**Get a single book**::
@api.route("/books/{book_id:int}", methods=["GET"])
async def get_book(req, resp, *, book_id):
async with async_session() as session:
book = await session.get(Book, book_id)
if book is None:
resp.status_code = 404
resp.media = {"error": "Book not found"}
return
resp.media = BookOut.model_validate(book).model_dump()
**Update a book**::
@api.route("/books/{book_id:int}", methods=["PUT"], check_existing=False,
request_model=BookIn)
async def update_book(req, resp, *, book_id):
data = await req.media()
async with async_session() as session:
book = await session.get(Book, book_id)
if book is None:
resp.status_code = 404
resp.media = {"error": "Book not found"}
return
for key, value in data.items():
setattr(book, key, value)
await session.commit()
await session.refresh(book)
resp.media = BookOut.model_validate(book).model_dump()
**Delete a book**::
@api.route("/books/{book_id:int}", methods=["DELETE"], check_existing=False)
async def delete_book(req, resp, *, book_id):
async with async_session() as session:
book = await session.get(Book, book_id)
if book is None:
resp.status_code = 404
resp.media = {"error": "Book not found"}
return
await session.delete(book)
await session.commit()
resp.status_code = 204
Run It
------
::
if __name__ == "__main__":
api.run()
Start the server and you'll see SQLAlchemy's SQL echo in the console.
The SQLite database file ``books.db`` is created automatically on first
startup.
Using PostgreSQL
----------------
To switch to PostgreSQL, just change the connection URL and driver::
$ uv pip install asyncpg
::
DATABASE_URL = "postgresql+asyncpg://user:pass@localhost/mydb"
Everything else stays the same. SQLAlchemy abstracts the database
differences so your application code doesn't need to change.
Tips
----
- Use ``async with async_session() as session`` for every request.
Don't share sessions across requests — each request should get its
own session and transaction.
- For complex queries, use SQLAlchemy's ``select()`` with ``.where()``,
``.order_by()``, ``.limit()``, and ``.offset()`` — it composes
naturally.
- In production, use connection pooling (SQLAlchemy does this by
default) and set pool size limits appropriate for your database.
- Consider `Alembic <https://alembic.sqlalchemy.org/>`_ for database
migrations — it tracks schema changes over time so you can evolve
your database without losing data.
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WebSocket Tutorial
==================
HTTP is request-response — the client asks, the server answers, and the
connection closes. WebSockets upgrade that into a persistent, bidirectional
channel where both sides can send messages at any time. This is what powers
chat apps, live dashboards, multiplayer games, and collaborative editors.
This tutorial builds a simple chat room to show how WebSockets work in
Responder.
How WebSockets Work
-------------------
1. The client sends a normal HTTP request with an ``Upgrade: websocket``
header.
2. The server accepts the upgrade and the connection switches protocols.
3. Both sides can now send messages freely — no more request/response.
4. Either side can close the connection at any time.
In Responder, WebSocket routes receive a ``ws`` object instead of
``req`` and ``resp``. The ``ws`` object has methods for accepting the
connection, sending and receiving data, and closing.
Echo Server
-----------
The simplest WebSocket — echoes everything back::
@api.route("/ws", websocket=True)
async def echo(ws):
await ws.accept()
while True:
data = await ws.receive_text()
await ws.send_text(f"Echo: {data}")
The ``await ws.accept()`` call completes the WebSocket handshake. After
that, you're in a loop — receive a message, send a response.
Test it with a WebSocket client::
$ pip install websocket-client
$ python -c "
import websocket
ws = websocket.create_connection('ws://localhost:5042/ws')
ws.send('hello')
print(ws.recv()) # Echo: hello
ws.close()
"
Chat Room
---------
A chat room needs to broadcast messages to all connected clients. We keep
a set of active connections and iterate through them when someone sends
a message::
from starlette.websockets import WebSocketDisconnect
connected = set()
@api.route("/chat", websocket=True)
async def chat(ws):
await ws.accept()
connected.add(ws)
try:
while True:
message = await ws.receive_text()
# Broadcast to all connected clients
for client in connected:
await client.send_text(message)
except WebSocketDisconnect:
pass
finally:
connected.discard(ws)
The ``try/finally`` block ensures we remove disconnected clients from
the set, even if the connection drops unexpectedly. Catching
``WebSocketDisconnect`` specifically (rather than bare ``Exception``)
makes the intent clear and avoids swallowing real bugs.
Data Formats
------------
WebSockets support three data formats:
**Text** — plain strings::
await ws.send_text("hello")
message = await ws.receive_text()
**JSON** — auto-serialized Python objects::
await ws.send_json({"type": "update", "data": [1, 2, 3]})
message = await ws.receive_json()
**Binary** — raw bytes, useful for images, audio, or custom protocols::
await ws.send_bytes(b"\x00\x01\x02")
data = await ws.receive_bytes()
HTML Client
-----------
Here's a minimal HTML page that connects to the chat room. The browser's
built-in ``WebSocket`` API handles everything — no libraries needed:
.. code-block:: html
<!DOCTYPE html>
<html>
<body>
<div id="messages"></div>
<input id="input" placeholder="Type a message..." />
<script>
const ws = new WebSocket("ws://localhost:5042/chat");
const messages = document.getElementById("messages");
const input = document.getElementById("input");
ws.onmessage = (event) => {
const p = document.createElement("p");
p.textContent = event.data;
messages.appendChild(p);
};
input.addEventListener("keypress", (e) => {
if (e.key === "Enter") {
ws.send(input.value);
input.value = "";
}
});
</script>
</body>
</html>
Save this as ``static/index.html`` and serve it with Responder's
built-in static file support.
Before-Request Hooks for WebSockets
------------------------------------
You can run code before a WebSocket connection is established, just like
HTTP before-request hooks. This is useful for authentication::
@api.before_request(websocket=True)
async def ws_auth(ws):
# Check for a token in the query string
# (WebSocket headers are limited in browsers)
await ws.accept()
WebSocket before-request hooks receive the ``ws`` object and must call
``await ws.accept()`` if they want the connection to proceed.
Connection Lifecycle
--------------------
WebSocket connections go through several states:
1. **Connecting** — the client sends an upgrade request
2. **Open** — after ``await ws.accept()``, both sides can send messages
3. **Closing** — either side initiates a close handshake
4. **Closed** — the connection is fully terminated
When a client disconnects (closes the tab, loses network), the next
``await ws.receive_text()`` raises ``WebSocketDisconnect``. Always
handle this — otherwise your server accumulates dead connections::
from starlette.websockets import WebSocketDisconnect
@api.route("/ws", websocket=True)
async def handler(ws):
await ws.accept()
try:
while True:
data = await ws.receive_text()
await ws.send_text(f"Got: {data}")
except WebSocketDisconnect:
print("Client disconnected")
You can also close connections from the server side::
await ws.close(code=1000) # 1000 = normal closure
Common close codes: ``1000`` (normal), ``1001`` (going away),
``1008`` (policy violation), ``1011`` (server error).
Testing WebSockets
------------------
Use Starlette's ``TestClient`` for WebSocket tests::
from starlette.testclient import TestClient
def test_echo():
client = TestClient(api)
with client.websocket_connect("/ws") as ws:
ws.send_text("hello")
assert ws.receive_text() == "Echo: hello"
The ``websocket_connect`` context manager handles the connection
lifecycle — it connects on enter and disconnects on exit.
You can also test that connections are properly rejected::
from starlette.websockets import WebSocketDisconnect
def test_websocket_404():
client = TestClient(api)
with pytest.raises(WebSocketDisconnect):
with client.websocket_connect("/nonexistent"):
pass
+31
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"""Mount marimo notebooks inside a Responder API.
Requirements:
pip install responder marimo
Usage:
python examples/marimo_mount.py
Then visit:
http://127.0.0.1:5042/hello → Responder JSON endpoint
http://127.0.0.1:5042/notebooks/ → Interactive marimo notebook
"""
import marimo
import responder
api = responder.API()
@api.route("/hello")
def hello(req, resp):
resp.media = {"message": "Hello from Responder!"}
# Mount marimo notebooks at /notebooks
server = marimo.create_asgi_app().with_app(path="", root="notebooks/hello.py")
api.mount("/notebooks", server.build())
if __name__ == "__main__":
api.run()
+76
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@@ -0,0 +1,76 @@
# Complete REST API example with Pydantic validation.
# https://responder.kennethreitz.org/tutorial-rest.html
from pydantic import BaseModel
import responder
class BookIn(BaseModel):
title: str
author: str
year: int
isbn: str | None = None
class BookOut(BaseModel):
id: int
title: str
author: str
year: int
isbn: str | None = None
api = responder.API(
title="Book Catalog",
version="1.0",
openapi="3.0.2",
docs_route="/docs",
)
books_db: dict[int, dict] = {}
next_id = 1
@api.route("/books", methods=["GET"])
def list_books(req, resp):
resp.media = list(books_db.values())
@api.route(
"/books",
methods=["POST"],
check_existing=False,
request_model=BookIn,
response_model=BookOut,
)
async def create_book(req, resp):
global next_id
data = await req.media()
book = {"id": next_id, **data}
books_db[next_id] = book
next_id += 1
resp.media = book
resp.status_code = 201
@api.route("/books/{book_id:int}", methods=["GET"])
def get_book(req, resp, *, book_id):
if book_id not in books_db:
resp.status_code = 404
resp.media = {"error": f"Book {book_id} not found"}
return
resp.media = books_db[book_id]
@api.route("/books/{book_id:int}", methods=["DELETE"], check_existing=False)
def delete_book(req, resp, *, book_id):
if book_id not in books_db:
resp.status_code = 404
resp.media = {"error": f"Book {book_id} not found"}
return
del books_db[book_id]
resp.status_code = 204
if __name__ == "__main__":
api.run()
+42
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@@ -0,0 +1,42 @@
# Server-Sent Events streaming example.
# https://responder.kennethreitz.org/tour.html#server-sent-events-sse
import asyncio
import responder
api = responder.API()
@api.route("/")
def index(req, resp):
resp.html = """
<!DOCTYPE html>
<html>
<body>
<h1>SSE Stream</h1>
<div id="events"></div>
<script>
const source = new EventSource("/stream");
const events = document.getElementById("events");
source.onmessage = (e) => {
const p = document.createElement("p");
p.textContent = e.data;
events.appendChild(p);
};
</script>
</body>
</html>
"""
@api.route("/stream")
async def stream(req, resp):
@resp.sse
async def events():
for i in range(20):
yield {"data": f"Event #{i}"}
await asyncio.sleep(0.5)
if __name__ == "__main__":
api.run()
+59
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@@ -0,0 +1,59 @@
# WebSocket chat room example.
# https://responder.kennethreitz.org/tutorial-websockets.html
from starlette.websockets import WebSocketDisconnect
import responder
api = responder.API()
connected = set()
@api.route("/")
def index(req, resp):
resp.html = """
<!DOCTYPE html>
<html>
<body>
<h1>Chat Room</h1>
<div id="messages" style="height:300px;overflow-y:scroll;border:1px solid #ccc;padding:10px;"></div>
<input id="input" placeholder="Type a message..." style="width:300px;" />
<script>
const ws = new WebSocket(`ws://${location.host}/chat`);
const messages = document.getElementById("messages");
const input = document.getElementById("input");
ws.onmessage = (e) => {
const p = document.createElement("p");
p.textContent = e.data;
messages.appendChild(p);
messages.scrollTop = messages.scrollHeight;
};
input.addEventListener("keypress", (e) => {
if (e.key === "Enter" && input.value) {
ws.send(input.value);
input.value = "";
}
});
</script>
</body>
</html>
""" # noqa: E501
@api.route("/chat", websocket=True)
async def chat(ws):
await ws.accept()
connected.add(ws)
try:
while True:
message = await ws.receive_text()
for client in connected:
await client.send_text(message)
except WebSocketDisconnect:
pass
finally:
connected.discard(ws)
if __name__ == "__main__":
api.run()
+57 -74
View File
@@ -8,11 +8,11 @@ requires = [
name = "responder"
description = "A familiar HTTP Service Framework for Python."
readme = "README.md"
license = {text = "Apache 2.0"}
license = { text = "Apache 2.0" }
authors = [
{ name = "Kenneth Reitz", email = "me@kennethreitz.org" },
]
requires-python = ">=3.9"
requires-python = ">=3.10"
classifiers = [
"Development Status :: 5 - Production/Stable",
"Environment :: Web Environment",
@@ -20,19 +20,21 @@ classifiers = [
"License :: OSI Approved :: Apache Software License",
"Operating System :: OS Independent",
"Programming Language :: Python",
"Programming Language :: Python :: 3",
"Programming Language :: Python :: 3.9",
"Programming Language :: Python :: 3 :: Only",
"Programming Language :: Python :: 3.10",
"Programming Language :: Python :: 3.11",
"Programming Language :: Python :: 3.12",
"Programming Language :: Python :: 3.13",
"Programming Language :: Python :: 3.14",
"Programming Language :: Python :: Free Threading",
"Programming Language :: Python :: Implementation :: CPython",
"Programming Language :: Python :: Implementation :: PyPy",
"Topic :: Internet :: WWW/HTTP",
]
dynamic = ["version"]
dynamic = [ "version" ]
dependencies = [
"a2wsgi",
"apispec>=1.0.0",
"apispec>=1",
"chardet",
"docopt-ng",
"graphene>=3",
@@ -42,17 +44,15 @@ dependencies = [
"pueblo[sfa-full]>=0.0.11",
"pydantic>=2",
"python-multipart",
"starlette[full]>=0.40",
"starlette[full]>=1",
"uvicorn[standard]",
]
[project.optional-dependencies]
develop = [
optional-dependencies.develop = [
"pyproject-fmt",
"ruff",
"validate-pyproject",
]
docs = [
optional-dependencies.docs = [
"alabaster<1.1",
"myst-parser",
"sphinx>=5,<9",
@@ -60,8 +60,8 @@ docs = [
"sphinx-copybutton",
"sphinx-design-elements",
]
release = ["build", "twine"]
test = [
optional-dependencies.release = [ "build", "twine" ]
optional-dependencies.test = [
"flask",
"mypy",
"pytest",
@@ -69,32 +69,22 @@ test = [
"pytest-mock",
"pytest-rerunfailures",
]
urls.Documentation = "https://responder.kennethreitz.org"
urls.Homepage = "https://github.com/kennethreitz/responder"
urls.Issues = "https://github.com/kennethreitz/responder/issues"
urls.Repository = "https://github.com/kennethreitz/responder"
scripts.responder = "responder.ext.cli:cli"
[project.scripts]
responder = "responder.ext.cli:cli"
[project.urls]
Homepage = "https://github.com/kennethreitz/responder"
Documentation = "https://responder.kennethreitz.org"
Repository = "https://github.com/kennethreitz/responder"
Issues = "https://github.com/kennethreitz/responder/issues"
[tool.setuptools.dynamic]
version = {attr = "responder.__version__.__version__"}
[tool.setuptools.package-data]
responder = ["py.typed"]
[tool.setuptools.packages.find]
exclude = ["tests"]
[tool.setuptools]
dynamic.version = { attr = "responder.__version__.__version__" }
package-data.responder = [ "py.typed", "ext/openapi/docs/*.html" ]
packages.find.exclude = [ "tests" ]
[tool.ruff]
line-length = 90
extend-exclude = [
"docs/source/conf.py",
]
lint.select = [
# Builtins
"A",
@@ -122,59 +112,20 @@ lint.select = [
# flake8-2020
"YTT",
]
lint.extend-ignore = [
"S101", # Allow use of `assert`.
"S101", # Allow use of `assert`.
]
lint.per-file-ignores."responder/util/cmd.py" = [ "A005" ] # Module shadows a Python standard-library module
lint.per-file-ignores."responder/util/cmd.py" = [ "A005" ] # Module shadows a Python standard-library module
lint.per-file-ignores."tests/*" = [
"ERA001", # Found commented-out code.
"S101", # Allow use of `assert`, and `print`.
]
[tool.pytest.ini_options]
addopts = """
-rfEXs -p pytester --strict-markers --verbosity=3
--cov --cov-report=term-missing --cov-report=xml
"""
filterwarnings = [
"error::UserWarning",
]
log_level = "DEBUG"
log_cli_level = "DEBUG"
log_format = "%(asctime)-15s [%(name)-36s] %(levelname)-8s: %(message)s"
minversion = "2.0"
testpaths = [
"responder",
"tests",
]
markers = [
]
xfail_strict = true
[tool.coverage.run]
branch = false
omit = [
"*.html",
"tests/*",
]
[tool.coverage.report]
fail_under = 0
show_missing = true
exclude_lines = [
"# pragma: no cover",
"raise NotImplemented",
]
[tool.mypy]
packages = [
"responder",
]
exclude = [
]
exclude = []
check_untyped_defs = true
explicit_package_bases = true
ignore_missing_imports = true
@@ -182,3 +133,35 @@ implicit_optional = true
install_types = true
namespace_packages = true
non_interactive = true
[tool.pytest]
ini_options.addopts = """
-rfEXs -p pytester --strict-markers --verbosity=3
--cov --cov-report=term-missing --cov-report=xml
"""
ini_options.filterwarnings = [
"error::UserWarning",
]
ini_options.log_level = "DEBUG"
ini_options.log_cli_level = "DEBUG"
ini_options.log_format = "%(asctime)-15s [%(name)-36s] %(levelname)-8s: %(message)s"
ini_options.minversion = "2.0"
ini_options.testpaths = [
"responder",
"tests",
]
ini_options.markers = []
ini_options.xfail_strict = true
[tool.coverage]
run.branch = false
run.omit = [
"*.html",
"tests/*",
]
report.exclude_lines = [
"# pragma: no cover",
"raise NotImplemented",
]
report.fail_under = 0
report.show_missing = true
+1 -1
View File
@@ -1 +1 @@
__version__ = "3.2.0"
__version__ = "3.6.0"
+82 -5
View File
@@ -1,4 +1,5 @@
import asyncio
import inspect
import os
from pathlib import Path
@@ -60,7 +61,34 @@ class API:
openapi_theme=DEFAULT_OPENAPI_THEME,
lifespan=None,
request_id=False,
enable_logging=False,
):
"""Create a new Responder API instance.
:param debug: If ``True``, enable debug mode with verbose error pages.
:param title: The title of the API, used in OpenAPI documentation.
:param version: The version string for the API (e.g. ``"1.0"``).
:param description: A longer description of the API for OpenAPI docs.
:param terms_of_service: URL to the API's terms of service.
:param contact: Contact information dict for the API (``name``, ``url``, ``email``).
:param license: License information dict (``name``, ``url``).
:param openapi: The OpenAPI version string (e.g. ``"3.0.2"``). Enables OpenAPI schema generation.
:param openapi_route: The URL path for the OpenAPI schema (default ``"/schema.yml"``).
:param static_dir: Directory for static files. Set to ``None`` to disable. Created automatically if missing.
:param static_route: URL prefix for serving static files (default ``"/static"``).
:param templates_dir: Directory for Jinja2 templates (default ``"templates"``).
:param auto_escape: If ``True``, auto-escape HTML/XML in templates.
:param secret_key: Secret key for signing cookie-based sessions. **Always set this in production.**
:param enable_hsts: If ``True``, redirect all HTTP requests to HTTPS.
:param docs_route: URL path for interactive API docs (e.g. ``"/docs"``). Enables OpenAPI if not already set.
:param cors: If ``True``, enable CORS middleware.
:param cors_params: Dict of CORS configuration (``allow_origins``, ``allow_methods``, etc.).
:param allowed_hosts: List of allowed hostnames (e.g. ``["example.com"]``). Defaults to ``["*"]``.
:param openapi_theme: Documentation UI theme: ``"swagger_ui"``, ``"redoc"``, ``"rapidoc"``, or ``"elements"``.
:param lifespan: An async context manager for startup/shutdown logic.
:param request_id: If ``True``, add ``X-Request-ID`` headers to all responses.
:param enable_logging: If ``True``, enable structured logging with per-request context (request ID, method, path, client IP).
""" # noqa: E501
self.background = BackgroundQueue()
self.secret_key = secret_key
@@ -132,17 +160,29 @@ class API:
self.templates = Templates(directory=templates_dir)
if request_id:
if request_id and not enable_logging:
import uuid as _uuid
def _add_request_id(req, resp):
rid = req.headers.get(
"X-Request-ID", str(_uuid.uuid4())
)
rid = req.headers.get("X-Request-ID", str(_uuid.uuid4()))
resp.headers["X-Request-ID"] = rid
self.router.after_request(_add_request_id)
if enable_logging:
import logging as _logging
from .ext.logging import LoggingMiddleware, get_logger, setup_logging
log_level = _logging.DEBUG if debug else _logging.INFO
setup_logging(level=log_level)
self.add_middleware(LoggingMiddleware)
self.log = get_logger("responder.app")
else:
import logging as _logging
self.log = _logging.getLogger("responder.app")
@property
def requests(self):
"""A test client connected to the ASGI app. Lazily initialized."""
@@ -150,12 +190,30 @@ class API:
@property
def static_app(self):
"""The Starlette ``StaticFiles`` application for serving static assets."""
if not hasattr(self, "_static_app"):
assert self.static_dir is not None
self._static_app = StaticFiles(directory=self.static_dir)
return self._static_app
def before_request(self, websocket=False):
"""Register a function to run before every request.
If the hook sets ``resp.status_code``, the route handler is skipped
and the response is sent immediately (short-circuiting).
:param websocket: If ``True``, register as a WebSocket before-request hook instead of HTTP.
Usage::
@api.before_request()
def check_auth(req, resp):
if "Authorization" not in req.headers:
resp.status_code = 401
resp.media = {"error": "unauthorized"}
""" # noqa: E501
def decorator(f):
self.router.before_request(f, websocket=websocket)
return f
@@ -180,6 +238,21 @@ class API:
return decorator
def add_middleware(self, middleware_cls, **middleware_config):
"""Add ASGI middleware to the application.
Middleware wraps the entire application and can inspect or modify
every request and response. Middleware is applied in reverse order —
the last middleware added runs first.
:param middleware_cls: A Starlette-compatible middleware class.
:param middleware_config: Keyword arguments passed to the middleware constructor.
Usage::
from starlette.middleware.httpsredirect import HTTPSRedirectMiddleware
api.add_middleware(HTTPSRedirectMiddleware)
"""
self.app = middleware_cls(self.app, **middleware_config)
def exception_handler(self, exception_cls):
@@ -200,7 +273,7 @@ class API:
req = Request(request.scope, request.receive, formats=get_formats())
resp = Response(req=req, formats=get_formats())
if asyncio.iscoroutinefunction(func):
if inspect.iscoroutinefunction(func):
await func(req, resp, exc)
else:
func(req, resp, exc)
@@ -501,6 +574,10 @@ class API:
uvicorn.run(self, host=address, port=port, **options)
def run(self, **kwargs):
"""Run the application. Shorthand for :meth:`serve` that inherits the ``debug`` setting.
:param kwargs: Keyword arguments passed through to :meth:`serve`.
""" # noqa: E501
if "debug" not in kwargs:
kwargs.update({"debug": self.debug})
self.serve(**kwargs)
+41 -1
View File
@@ -1,5 +1,6 @@
import asyncio
import concurrent.futures
import inspect
import multiprocessing
import traceback
@@ -9,7 +10,33 @@ __all__ = ["BackgroundQueue"]
class BackgroundQueue:
"""A queue for running tasks in background threads.
Uses a ``ThreadPoolExecutor`` sized to the number of CPUs. Access it
via ``api.background``.
Usage::
# As a decorator — fire and forget
@api.background.task
def send_email(to, subject):
...
send_email("user@example.com", "Hello")
# Direct submission
future = api.background.run(send_email, "user@example.com", "Hello")
# As a callable (supports async functions)
await api.background(send_email, "user@example.com", "Hello")
"""
def __init__(self, n=None):
"""Create a new background queue.
:param n: Number of worker threads. Defaults to CPU count.
"""
if n is None:
n = multiprocessing.cpu_count()
@@ -18,11 +45,24 @@ class BackgroundQueue:
self.results = []
def run(self, f, *args, **kwargs):
"""Submit a function to run in a background thread.
:param f: The function to run.
:returns: A ``concurrent.futures.Future`` for the result.
"""
f = self.pool.submit(f, *args, **kwargs)
self.results.append(f)
return f
def task(self, f):
"""Decorator that wraps a function to run in the background thread pool.
The decorated function returns a ``Future`` instead of blocking.
Exceptions are printed to stderr via traceback.
:param f: The function to wrap.
"""
def on_future_done(fs):
try:
fs.result()
@@ -37,6 +77,6 @@ class BackgroundQueue:
return do_task
async def __call__(self, func, *args, **kwargs) -> None:
if asyncio.iscoroutinefunction(func):
if inspect.iscoroutinefunction(func):
return await asyncio.create_task(func(*args, **kwargs))
return await run_in_threadpool(func, *args, **kwargs)
+47 -2
View File
@@ -4,12 +4,43 @@ from .templates import GRAPHIQL
class GraphQLView:
"""A class-based view that serves a GraphQL API.
Handles query resolution from multiple sources (JSON body, query
parameters, raw request text) and renders the GraphiQL IDE for
browser requests.
:param api: The Responder API instance.
:param schema: A Graphene schema instance.
"""
def __init__(self, *, api, schema):
self.api = api
self.schema = schema
@staticmethod
def _parse_variables(raw):
"""Parse variables from a string (query param) or return as-is (dict)."""
if raw is None:
return None
if isinstance(raw, str):
try:
return json.loads(raw)
except (json.JSONDecodeError, ValueError):
return None
return raw
@staticmethod
async def _resolve_graphql_query(req, resp):
"""Extract query, variables, and operationName from the request.
Supports multiple input sources, checked in order:
1. JSON body (``Content-Type: application/json``)
2. Form data (``Content-Type: application/x-www-form-urlencoded``)
3. Query parameters (``?query=...&variables=...&operationName=...``)
4. Raw request text
"""
if "json" in req.mimetype:
json_media = await req.media("json")
if "query" not in json_media:
@@ -22,9 +53,22 @@ class GraphQLView:
json_media.get("operationName"),
)
# Support query/q in params.
if "form" in req.mimetype:
form_data = await req.media("form")
if "query" in form_data:
return (
form_data["query"],
GraphQLView._parse_variables(form_data.get("variables")),
form_data.get("operationName"),
)
# Support query/variables/operationName in query params.
if "query" in req.params:
return req.params["query"], None, None
return (
req.params["query"],
GraphQLView._parse_variables(req.params.get("variables")),
req.params.get("operationName"),
)
if "q" in req.params:
return req.params["q"], None, None
@@ -32,6 +76,7 @@ class GraphQLView:
return await req.text, None, None
async def graphql_response(self, req, resp):
"""Process a GraphQL request and populate the response."""
show_graphiql = req.method == "get" and req.accepts("text/html")
if show_graphiql:
+181
View File
@@ -0,0 +1,181 @@
"""Structured logging with per-request context.
Provides a logging setup that automatically includes request metadata
(request ID, method, path, client IP) in every log message emitted
during request handling.
Usage::
api = responder.API(enable_logging=True)
# In any route or middleware:
from responder.ext.logging import get_logger
logger = get_logger(__name__)
@api.route("/")
def index(req, resp):
logger.info("handling request")
# => 2026-03-24 12:00:00 [INFO] app — handling request [GET /] [req:abc123] [client:127.0.0.1]
"""
from __future__ import annotations
import logging
import time
import uuid
from contextvars import ContextVar
__all__ = ["get_logger", "RequestContext", "RequestContextFilter", "LoggingMiddleware"]
# Context variables for per-request metadata.
_request_id: ContextVar[str] = ContextVar("request_id", default="-")
_request_method: ContextVar[str] = ContextVar("request_method", default="-")
_request_path: ContextVar[str] = ContextVar("request_path", default="-")
_client_ip: ContextVar[str] = ContextVar("client_ip", default="-")
class RequestContext:
"""Read-only access to the current request's logging context."""
@staticmethod
def get_request_id() -> str:
return _request_id.get()
@staticmethod
def get_method() -> str:
return _request_method.get()
@staticmethod
def get_path() -> str:
return _request_path.get()
@staticmethod
def get_client_ip() -> str:
return _client_ip.get()
class RequestContextFilter(logging.Filter):
"""A logging filter that injects request context into log records.
Adds ``request_id``, ``request_method``, ``request_path``, and
``client_ip`` attributes to every log record, so they can be used
in format strings.
"""
def filter(self, record: logging.LogRecord) -> bool:
record.request_id = _request_id.get() # type: ignore[attr-defined]
record.request_method = _request_method.get() # type: ignore[attr-defined]
record.request_path = _request_path.get() # type: ignore[attr-defined]
record.client_ip = _client_ip.get() # type: ignore[attr-defined]
return True
# Default format that includes request context.
DEFAULT_LOG_FORMAT = (
"%(asctime)s [%(levelname)s] %(name)s -- %(message)s "
"[%(request_method)s %(request_path)s] "
"[req:%(request_id)s] [client:%(client_ip)s]"
)
def get_logger(name: str | None = None) -> logging.Logger:
"""Get a logger with the request context filter attached.
:param name: Logger name (typically ``__name__``).
:returns: A :class:`logging.Logger` with request context available.
"""
logger = logging.getLogger(name)
# Avoid adding duplicate filters.
if not any(isinstance(f, RequestContextFilter) for f in logger.filters):
logger.addFilter(RequestContextFilter())
return logger
def setup_logging(level: int = logging.INFO) -> None:
"""Configure the root logger with request-context-aware formatting.
:param level: The logging level (default ``INFO``).
"""
root = logging.getLogger()
root.setLevel(level)
# Only add our handler if the root logger has no handlers yet,
# or if none of them use our filter.
has_context_handler = any(
any(isinstance(f, RequestContextFilter) for f in h.filters)
for h in root.handlers
)
if not has_context_handler:
handler = logging.StreamHandler()
handler.setLevel(level)
handler.addFilter(RequestContextFilter())
handler.setFormatter(logging.Formatter(DEFAULT_LOG_FORMAT))
root.addHandler(handler)
class LoggingMiddleware:
"""ASGI middleware that sets per-request context variables.
For each HTTP request, this middleware:
1. Extracts or generates a request ID
2. Sets context variables for method, path, and client IP
3. Logs the request and response with timing information
"""
def __init__(self, app, logger_name: str = "responder.access"):
self.app = app
self.logger = get_logger(logger_name)
async def __call__(self, scope, receive, send):
if scope["type"] not in ("http", "websocket"):
await self.app(scope, receive, send)
return
# Extract request metadata.
headers = dict(scope.get("headers", []))
request_id = (
headers.get(b"x-request-id", b"").decode() or uuid.uuid4().hex[:8]
)
method = scope.get("method", "WS")
path = scope.get("path", "/")
client = scope.get("client")
client_ip = client[0] if client else "-"
# Set context variables for the duration of this request.
tok_id = _request_id.set(request_id)
tok_method = _request_method.set(method)
tok_path = _request_path.set(path)
tok_ip = _client_ip.set(client_ip)
# Track response status.
status_code = None
async def send_wrapper(message):
nonlocal status_code
if message["type"] == "http.response.start":
status_code = message.get("status")
# Inject request ID into response headers.
headers_list = list(message.get("headers", []))
headers_list.append((b"x-request-id", request_id.encode()))
message = {**message, "headers": headers_list}
await send(message)
start = time.perf_counter()
try:
await self.app(scope, receive, send_wrapper)
finally:
duration_ms = (time.perf_counter() - start) * 1000
if scope["type"] == "http":
self.logger.info(
"%s %s%s (%.1fms)",
method,
path,
status_code or "?",
duration_ms,
)
# Reset context variables.
_request_id.reset(tok_id)
_request_method.reset(tok_method)
_request_path.reset(tok_path)
_client_ip.reset(tok_ip)
+3 -1
View File
@@ -129,7 +129,9 @@ class OpenAPISchema:
op["requestBody"] = {
"content": {
"application/json": {
"schema": {"$ref": f"#/components/schemas/{model_name}"}
"schema": {
"$ref": f"#/components/schemas/{model_name}"
}
}
}
}
+1 -3
View File
@@ -38,9 +38,7 @@ class RateLimiter:
def _cleanup(self, key):
now = time.time()
cutoff = now - self.period
self._buckets[key] = [
t for t in self._buckets[key] if t > cutoff
]
self._buckets[key] = [t for t in self._buckets[key] if t > cutoff]
def check(self, req, resp):
"""Check rate limit. Sets 429 status if exceeded."""
+79 -10
View File
@@ -49,6 +49,12 @@ class CaseInsensitiveDict(dict):
class QueryDict(dict):
"""A dictionary for query string parameters that handles multi-value keys.
Single-value access returns the last value for a key. Use :meth:`get_list`
to retrieve all values for a multi-value parameter.
"""
def __init__(self, query_string):
self.update(parse_qs(query_string))
@@ -117,6 +123,13 @@ class QueryDict(dict):
class Request:
"""An HTTP request, passed to each view as the first argument.
Provides access to headers, cookies, query parameters, the request body,
session data, and more. Most properties are synchronous; reading the body
(via :attr:`content`, :attr:`text`, or :meth:`media`) requires ``await``.
"""
__slots__ = [
"_starlette",
"formats",
@@ -153,6 +166,7 @@ class Request:
@property
def mimetype(self):
"""The MIME type of the request body, from the ``Content-Type`` header."""
return self.headers.get("Content-Type", "")
@property
@@ -270,6 +284,7 @@ class Request:
@property
def is_secure(self):
"""``True`` if the request was made over HTTPS."""
return self.url.scheme == "https"
def accepts(self, content_type):
@@ -315,6 +330,22 @@ def content_setter(mimetype):
class Response:
"""An HTTP response, passed to each view as the second argument.
Mutate this object to control what gets sent back to the client. Set
:attr:`text`, :attr:`html`, :attr:`media`, or :attr:`content` to define
the body. Use :attr:`headers` and :meth:`set_cookie` to control metadata.
:var text: Set the response body as plain text (sets ``Content-Type: text/plain``).
:var html: Set the response body as HTML (sets ``Content-Type: text/html``).
:var media: Set a Python object (dict, list) to be serialized as JSON (or negotiated format).
:var content: Set the raw response body as bytes.
:var status_code: The HTTP status code (e.g. ``200``, ``404``). Defaults to ``200`` if not set.
:var headers: A dict of response headers.
:var cookies: A ``SimpleCookie`` holding cookies to set on the response.
:var session: A dict of session data. Changes are persisted in a signed cookie.
""" # noqa: E501
__slots__ = [
"req",
"status_code",
@@ -334,23 +365,34 @@ class Response:
def __init__(self, req, *, formats):
self.req = req
#: The HTTP Status Code to use for the Response.
self.status_code: int | None = None
self.content = None #: A bytes representation of the response body.
self.content = None
self.mimetype = None
self.encoding = DEFAULT_ENCODING
self.media = None #: A Python object that will be content-negotiated and
#: sent back to the client. Typically, in JSON formatting.
self.media = None
self._stream = None
self.headers = {} #: A Python dictionary of ``{key: value}``,
#: representing the headers of the response.
self.headers = {}
self.formats = formats
self.cookies: SimpleCookie = SimpleCookie() #: The cookies set in the Response
self.session = (
req.session
) #: The cookie-based session data, in dict form, to add to the Response.
self.cookies: SimpleCookie = SimpleCookie()
self.session = req.session
def stream(self, func, *args, **kwargs):
"""Set up a streaming response from an async generator function.
The generator yields chunks of bytes that are sent to the client
as they are produced, without buffering the full response in memory.
Usage::
@api.route("/stream")
async def stream_data(req, resp):
@resp.stream
async def body():
for i in range(10):
yield f"chunk {i}\\n".encode()
:param func: An async generator function that yields response chunks.
"""
assert inspect.isasyncgenfunction(func)
self._stream = functools.partial(func, *args, **kwargs)
@@ -451,6 +493,12 @@ class Response:
self.mimetype = guessed or "application/octet-stream"
def redirect(self, location, *, set_text=True, status_code=HTTP_301):
"""Redirect the client to a different URL.
:param location: The URL to redirect to.
:param set_text: If ``True``, set a default redirect message as the body.
:param status_code: The HTTP status code (default ``301``).
"""
self.status_code = status_code
if set_text:
self.text = f"Redirecting to: {location}"
@@ -496,6 +544,25 @@ class Response:
secure=False,
httponly=True,
):
"""Set a cookie on the response with full control over directives.
:param key: The cookie name.
:param value: The cookie value.
:param expires: Expiration date string (e.g. ``"Thu, 01 Jan 2026 00:00:00 GMT"``).
:param path: URL path the cookie applies to (default ``"/"``).
:param domain: Domain the cookie is valid for.
:param max_age: Maximum age in seconds before the cookie expires.
:param secure: If ``True``, cookie is only sent over HTTPS.
:param httponly: If ``True`` (default), cookie is inaccessible to JavaScript.
Usage::
resp.set_cookie(
"token", value="abc123",
max_age=3600, secure=True, httponly=True,
)
"""
self.cookies[key] = value
morsel = self.cookies[key]
if expires is not None:
@@ -534,10 +601,12 @@ class Response:
@property
def ok(self):
"""``True`` if the status code is in the 2xx range (success)."""
return 200 <= self.status_code_safe < 300
@property
def status_code_safe(self) -> int:
"""Return the status code, raising ``RuntimeError`` if it hasn't been set."""
if self.status_code is None:
raise RuntimeError("HTTP status code has not been defined")
return self.status_code
+96 -57
View File
@@ -1,14 +1,18 @@
from __future__ import annotations
import asyncio
import inspect
import re
import traceback
from collections import defaultdict
from collections.abc import Callable
from typing import Any, Union
__all__ = ["Route", "WebSocketRoute", "Router"]
from starlette.concurrency import run_in_threadpool
from starlette.exceptions import HTTPException
from starlette.types import ASGIApp
from starlette.types import ASGIApp, Receive, Scope, Send
from starlette.websockets import WebSocket, WebSocketClose
from . import status_codes
@@ -28,9 +32,9 @@ _CONVERTORS = {
PARAM_RE = re.compile("{([a-zA-Z_][a-zA-Z0-9_]*)(:[a-zA-Z_][a-zA-Z0-9_]*)?}")
def compile_path(path):
def compile_path(path: str) -> tuple[re.Pattern, dict[str, type]]:
path_re = "^"
param_convertors = {}
param_convertors: dict[str, type] = {}
idx = 0
for match in PARAM_RE.finditer(path):
@@ -54,40 +58,55 @@ def compile_path(path):
class BaseRoute:
def matches(self, scope):
def matches(self, scope: Scope) -> tuple[bool, dict]:
raise NotImplementedError()
async def __call__(self, scope, receive, send):
async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
raise NotImplementedError()
class Route(BaseRoute):
def __init__(self, route, endpoint, *, before_request=False, methods=None):
"""An HTTP route that maps a URL pattern to an endpoint.
Supports path parameters with type convertors (``{id:int}``, ``{slug:str}``,
``{pk:uuid}``, ``{value:float}``, ``{rest:path}``).
"""
def __init__(
self,
route: str,
endpoint: Callable,
*,
before_request: bool = False,
methods: list[str] | None = None,
) -> None:
assert route.startswith("/"), "Route path must start with '/'"
self.route = route
self.endpoint = endpoint
self.before_request = before_request
self.methods = {m.upper() for m in methods} if methods else None
self.methods: set[str] | None = {m.upper() for m in methods} if methods else None
self.path_re: re.Pattern
self.param_convertors: dict[str, type]
self.path_re, self.param_convertors = compile_path(route)
# Strip type annotations for URL generation (e.g. {id:int} -> {id})
self._url_template = PARAM_RE.sub(r"{\1}", route)
def __repr__(self):
def __repr__(self) -> str:
return f"<Route {self.route!r}={self.endpoint!r}>"
def url(self, **params):
def url(self, **params: Any) -> str:
return self._url_template.format(**params)
@property
def endpoint_name(self):
def endpoint_name(self) -> str:
return self.endpoint.__name__
@property
def description(self):
def description(self) -> str | None:
return self.endpoint.__doc__
def matches(self, scope):
def matches(self, scope: Scope) -> tuple[bool, dict]:
if scope["type"] != "http":
return False, {}
@@ -106,7 +125,7 @@ class Route(BaseRoute):
return True, {"path_params": {**matched_params}}
async def __call__(self, scope, receive, send):
async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
request = Request(scope, receive, formats=get_formats())
response = Response(req=request, formats=get_formats())
@@ -114,7 +133,7 @@ class Route(BaseRoute):
before_requests = scope.get("before_requests", [])
for before_request in before_requests.get("http", []):
if asyncio.iscoroutinefunction(before_request):
if inspect.iscoroutinefunction(before_request):
await before_request(request, response)
else:
await run_in_threadpool(before_request, request, response)
@@ -160,7 +179,7 @@ class Route(BaseRoute):
for view in views:
# Check __call__ for class-based views (e.g. GraphQL)
if asyncio.iscoroutinefunction(view) or asyncio.iscoroutinefunction(
if inspect.iscoroutinefunction(view) or inspect.iscoroutinefunction(
view.__call__
):
await view(request, response, **path_params)
@@ -173,13 +192,13 @@ class Route(BaseRoute):
try:
validated = resp_model(**response.media)
response.media = validated.model_dump()
except Exception:
except (ValueError, TypeError):
pass # Don't break the response if serialization fails
# Run after-request hooks
after_requests = scope.get("after_requests", [])
for after_request in after_requests:
if asyncio.iscoroutinefunction(after_request):
if inspect.iscoroutinefunction(after_request):
await after_request(request, response)
else:
await run_in_threadpool(after_request, request, response)
@@ -189,38 +208,46 @@ class Route(BaseRoute):
await response(scope, receive, send)
def __eq__(self, other):
def __eq__(self, other: object) -> bool:
if not isinstance(other, Route):
return NotImplemented
return self.route == other.route and self.endpoint == other.endpoint
def __hash__(self):
def __hash__(self) -> int:
return hash(self.route) ^ hash(self.endpoint) ^ hash(self.before_request)
class WebSocketRoute(BaseRoute):
def __init__(self, route, endpoint, *, before_request=False):
"""A WebSocket route that maps a URL pattern to a WebSocket handler."""
def __init__(
self, route: str, endpoint: Callable, *, before_request: bool = False
) -> None:
assert route.startswith("/"), "Route path must start with '/'"
self.route = route
self.endpoint = endpoint
self.before_request = before_request
self.path_re: re.Pattern
self.param_convertors: dict[str, type]
self.path_re, self.param_convertors = compile_path(route)
self._url_template = PARAM_RE.sub(r"{\1}", route)
def __repr__(self):
def __repr__(self) -> str:
return f"<Route {self.route!r}={self.endpoint!r}>"
def url(self, **params):
def url(self, **params: Any) -> str:
return self._url_template.format(**params)
@property
def endpoint_name(self):
def endpoint_name(self) -> str:
return self.endpoint.__name__
@property
def description(self):
def description(self) -> str | None:
return self.endpoint.__doc__
def matches(self, scope):
def matches(self, scope: Scope) -> tuple[bool, dict]:
if scope["type"] != "websocket":
return False, {}
@@ -236,7 +263,7 @@ class WebSocketRoute(BaseRoute):
return True, {"path_params": {**matched_params}}
async def __call__(self, scope, receive, send):
async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
ws = WebSocket(scope, receive, send)
before_requests = scope.get("before_requests", [])
@@ -245,41 +272,53 @@ class WebSocketRoute(BaseRoute):
await self.endpoint(ws)
def __eq__(self, other):
def __eq__(self, other: object) -> bool:
if not isinstance(other, WebSocketRoute):
return NotImplemented
return self.route == other.route and self.endpoint == other.endpoint
def __hash__(self):
def __hash__(self) -> int:
return hash(self.route) ^ hash(self.endpoint) ^ hash(self.before_request)
class Router:
def __init__(
self, routes=None, default_response=None, before_requests=None, lifespan=None
):
self.routes = [] if routes is None else list(routes)
"""The core router that dispatches incoming requests to matching routes.
self.apps: dict[str, ASGIApp] = {}
self.default_endpoint = (
Handles route matching, before/after request hooks, lifespan events,
and mounted sub-applications.
"""
def __init__(
self,
routes: list[BaseRoute] | None = None,
default_response: Callable | None = None,
before_requests: dict[str, list[Callable]] | None = None,
lifespan: Callable | None = None,
) -> None:
self.routes: list[BaseRoute] = [] if routes is None else list(routes)
self.apps: dict[str, Union[ASGIApp, Any]] = {}
self.default_endpoint: Callable = (
self.default_response if default_response is None else default_response
)
self.before_requests = (
self.before_requests: dict[str, list[Callable]] = (
{"http": [], "ws": []} if before_requests is None else before_requests
)
self.after_requests: list = []
self.events = defaultdict(list)
self.after_requests: list[Callable] = []
self.events: defaultdict[str, list[Callable]] = defaultdict(list)
self._lifespan_handler = lifespan
def add_route(
self,
route=None,
endpoint=None,
route: str | None = None,
endpoint: Callable | None = None,
*,
default=False,
websocket=False,
before_request=False,
check_existing=False,
methods=None,
):
default: bool = False,
websocket: bool = False,
before_request: bool = False,
check_existing: bool = False,
methods: list[str] | None = None,
) -> None:
"""Adds a route to the router.
:param route: A string representation of the route
:param endpoint: The endpoint for the route -- can be callable, or class.
@@ -308,40 +347,40 @@ class Router:
self.routes.append(route)
def mount(self, route, app):
def mount(self, route: str, app: Any) -> None:
"""Mounts ASGI / WSGI applications at a given route"""
self.apps.update({route: app})
def add_event_handler(self, event_type, handler):
def add_event_handler(self, event_type: str, handler: Callable) -> None:
assert event_type in (
"startup",
"shutdown",
), f"Only 'startup' and 'shutdown' events are supported, not {event_type}."
self.events[event_type].append(handler)
async def trigger_event(self, event_type):
async def trigger_event(self, event_type: str) -> None:
for handler in self.events.get(event_type, []):
if asyncio.iscoroutinefunction(handler):
if inspect.iscoroutinefunction(handler):
await handler()
else:
handler()
def before_request(self, endpoint, websocket=False):
def before_request(self, endpoint: Callable, websocket: bool = False) -> None:
if websocket:
self.before_requests.setdefault("ws", []).append(endpoint)
else:
self.before_requests.setdefault("http", []).append(endpoint)
def after_request(self, endpoint):
def after_request(self, endpoint: Callable) -> None:
self.after_requests.append(endpoint)
def url_for(self, endpoint, **params):
def url_for(self, endpoint: Callable | str, **params: Any) -> str | None:
for route in self.routes:
if endpoint in (route.endpoint, route.endpoint.__name__):
return route.url(**params)
return None
async def default_response(self, scope, receive, send):
async def default_response(self, scope: Scope, receive: Receive, send: Send) -> None:
if scope["type"] == "websocket":
websocket_close = WebSocketClose()
await websocket_close(scope, receive, send)
@@ -352,7 +391,7 @@ class Router:
raise HTTPException(status_code=status_codes.HTTP_404) # type: ignore[attr-defined]
def _resolve_route(self, scope):
def _resolve_route(self, scope: Scope) -> BaseRoute | None:
for route in self.routes:
matches, child_scope = route.matches(scope)
if matches:
@@ -360,7 +399,7 @@ class Router:
return route
return None
async def lifespan(self, scope, receive, send):
async def lifespan(self, scope: Scope, receive: Receive, send: Send) -> None:
message = await receive()
assert message["type"] == "lifespan.startup"
@@ -395,7 +434,7 @@ class Router:
await send({"type": "lifespan.shutdown.complete"})
async def __call__(self, scope, receive, send):
async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
assert scope["type"] in ("http", "websocket", "lifespan")
if scope["type"] == "lifespan":
@@ -418,7 +457,7 @@ class Router:
# Call into a submounted app, if one exists.
for path_prefix, app in self.apps.items():
if path.startswith(path_prefix):
scope["path"] = path[len(path_prefix) :]
scope["path"] = path[len(path_prefix) :] or "/"
scope["root_path"] = root_path + path_prefix
try:
await app(scope, receive, send)
+63 -11
View File
@@ -4,14 +4,14 @@ import time
import pytest
from starlette.testclient import TestClient as StarletteTestClient
from starlette.websockets import WebSocketDisconnect
import responder
from responder.background import BackgroundQueue
from responder.models import CaseInsensitiveDict, QueryDict, Response
from responder.models import QueryDict
from responder.routes import Route, WebSocketRoute
from responder.templates import Templates
# --- api.py coverage ---
@@ -78,7 +78,10 @@ def test_background_task_exception(capsys):
raise ValueError("task failed")
future = failing_task()
future.result # wait for completion
try:
future.result() # wait for completion
except ValueError:
pass
time.sleep(0.2) # let the done callback fire
captured = capsys.readouterr()
@@ -302,7 +305,7 @@ def test_yaml_content_negotiation(api):
def test_websocket_404(api):
"""Lines 308-310: WebSocket to unknown route gets closed."""
client = StarletteTestClient(api)
with pytest.raises(Exception):
with pytest.raises(WebSocketDisconnect):
with client.websocket_connect("ws://;/nonexistent"):
pass
@@ -325,9 +328,7 @@ def test_websocket_route_params():
pass
route = WebSocketRoute("/ws/{room_id:int}", handler)
matches, scope = route.matches(
{"type": "websocket", "path": "/ws/42"}
)
matches, scope = route.matches({"type": "websocket", "path": "/ws/42"})
assert matches is True
assert scope["path_params"] == {"room_id": 42}
@@ -591,7 +592,10 @@ def test_pydantic_schema():
from pydantic import BaseModel
api = responder.API(
title="Test", version="1.0", openapi="3.0.2", allowed_hosts=[";"],
title="Test",
version="1.0",
openapi="3.0.2",
allowed_hosts=[";"],
)
@api.schema("Pet")
@@ -611,7 +615,10 @@ def test_pydantic_request_response_models():
from pydantic import BaseModel
api = responder.API(
title="Test", version="1.0", openapi="3.0.2", allowed_hosts=[";"],
title="Test",
version="1.0",
openapi="3.0.2",
allowed_hosts=[";"],
)
class ItemIn(BaseModel):
@@ -623,8 +630,7 @@ def test_pydantic_request_response_models():
name: str
price: float
@api.route("/items", methods=["POST"],
request_model=ItemIn, response_model=ItemOut)
@api.route("/items", methods=["POST"], request_model=ItemIn, response_model=ItemOut)
async def create(req, resp):
data = await req.media()
resp.media = {"id": 1, **data}
@@ -660,3 +666,49 @@ def test_templates_context(tmp_path):
result = templates.render("test.html")
assert "hello" in result
assert "world" in result
def test_static_file_serving(tmp_path):
"""Verify static files are served correctly from the static directory."""
static_dir = tmp_path / "static"
static_dir.mkdir()
(static_dir / "style.css").write_text("body { color: red; }")
(static_dir / "app.js").write_text("console.log('hello');")
api = responder.API(
static_dir=str(static_dir),
static_route="/static",
allowed_hosts=[";"],
)
# CSS file served with correct content
r = api.requests.get("http://;/static/style.css")
assert r.status_code == 200
assert "body { color: red; }" in r.text
assert "text/css" in r.headers.get("content-type", "")
# JS file served with correct content
r = api.requests.get("http://;/static/app.js")
assert r.status_code == 200
assert "console.log" in r.text
# Missing file returns 404
r = api.requests.get("http://;/static/missing.txt")
assert r.status_code == 404
def test_static_index_fallback(tmp_path):
"""Verify static index.html is served as default route."""
static_dir = tmp_path / "static"
static_dir.mkdir()
(static_dir / "index.html").write_text("<h1>SPA</h1>")
api = responder.API(
static_dir=str(static_dir),
allowed_hosts=[";"],
)
api.add_route("/", static=True)
r = api.requests.get("http://;/")
assert r.status_code == 200
assert "<h1>SPA</h1>" in r.text
+171
View File
@@ -1,4 +1,6 @@
# ruff: noqa: E402
import json
import pytest
graphene = pytest.importorskip("graphene")
@@ -17,6 +19,45 @@ def schema():
return graphene.Schema(query=Query)
@pytest.fixture
def mutation_schema():
class Query(graphene.ObjectType):
hello = graphene.String(name=graphene.String(default_value="stranger"))
def resolve_hello(self, info, name):
return f"Hello {name}"
class CreateUser(graphene.Mutation):
class Arguments:
name = graphene.String(required=True)
ok = graphene.Boolean()
name = graphene.String()
def mutate(self, info, name):
return CreateUser(ok=True, name=name)
class Mutation(graphene.ObjectType):
create_user = CreateUser.Field()
return graphene.Schema(query=Query, mutation=Mutation)
@pytest.fixture
def multi_op_schema():
class Query(graphene.ObjectType):
hello = graphene.String(name=graphene.String(default_value="stranger"))
goodbye = graphene.String(name=graphene.String(default_value="stranger"))
def resolve_hello(self, info, name):
return f"Hello {name}"
def resolve_goodbye(self, info, name):
return f"Goodbye {name}"
return graphene.Schema(query=Query)
def test_graphql_schema_query_querying(api, schema):
api.add_route("/", GraphQLView(schema=schema, api=api))
r = api.requests.get("http://;/?q={ hello }", headers={"Accept": "json"})
@@ -63,3 +104,133 @@ def test_graphql_error_response(api, schema):
api.add_route("/", GraphQLView(schema=schema, api=api))
r = api.requests.post("http://;/", json={"query": "{ nonexistent }"})
assert "errors" in r.json()
def test_graphql_variables_json(api, schema):
"""Variables passed via JSON body."""
api.add_route("/", GraphQLView(schema=schema, api=api))
r = api.requests.post(
"http://;/",
json={
"query": "query Hello($name: String!) { hello(name: $name) }",
"variables": {"name": "Alice"},
},
)
assert r.json() == {"data": {"hello": "Hello Alice"}}
def test_graphql_variables_query_param(api, schema):
"""Variables passed as JSON string in query parameter."""
api.add_route("/", GraphQLView(schema=schema, api=api))
variables = json.dumps({"name": "Bob"})
r = api.requests.get(
f"http://;/?query=query Hello($name: String!) "
f"{{ hello(name: $name) }}&variables={variables}",
headers={"Accept": "json"},
)
assert r.json() == {"data": {"hello": "Hello Bob"}}
def test_graphql_operation_name_json(api, multi_op_schema):
"""operationName selects which operation to run."""
api.add_route("/", GraphQLView(schema=multi_op_schema, api=api))
query = """
query SayHello { hello }
query SayGoodbye { goodbye }
"""
r = api.requests.post(
"http://;/",
json={
"query": query,
"operationName": "SayHello",
},
)
data = r.json()
assert data["data"]["hello"] == "Hello stranger"
def test_graphql_operation_name_query_param(api, multi_op_schema):
"""operationName via query parameter."""
api.add_route("/", GraphQLView(schema=multi_op_schema, api=api))
query = "query SayHello { hello } query SayGoodbye { goodbye }"
r = api.requests.get(
f"http://;/?query={query}&operationName=SayGoodbye",
headers={"Accept": "json"},
)
data = r.json()
assert data["data"]["goodbye"] == "Goodbye stranger"
def test_graphql_mutation(api, mutation_schema):
"""Mutations work via JSON body."""
api.add_route("/", GraphQLView(schema=mutation_schema, api=api))
r = api.requests.post(
"http://;/",
json={
"query": 'mutation { createUser(name: "Eve") { ok name } }',
},
)
data = r.json()
assert data["data"]["createUser"]["ok"] is True
assert data["data"]["createUser"]["name"] == "Eve"
def test_graphql_mutation_with_variables(api, mutation_schema):
"""Mutations with variables."""
api.add_route("/", GraphQLView(schema=mutation_schema, api=api))
r = api.requests.post(
"http://;/",
json={
"query": "mutation CreateUser($name: String!) "
"{ createUser(name: $name) { ok name } }",
"variables": {"name": "Frank"},
},
)
data = r.json()
assert data["data"]["createUser"]["ok"] is True
assert data["data"]["createUser"]["name"] == "Frank"
def test_graphql_context_access(api):
"""Resolvers can access request and response via info.context."""
class Query(graphene.ObjectType):
method = graphene.String()
def resolve_method(self, info):
return info.context["request"].method
schema = graphene.Schema(query=Query)
api.add_route("/", GraphQLView(schema=schema, api=api))
r = api.requests.post("http://;/", json={"query": "{ method }"})
assert r.json() == {"data": {"method": "post"}}
def test_graphql_malformed_query(api, schema):
"""Malformed GraphQL syntax returns errors."""
api.add_route("/", GraphQLView(schema=schema, api=api))
r = api.requests.post("http://;/", json={"query": "{ this is not valid"})
data = r.json()
assert "errors" in data
assert len(data["errors"]) > 0
def test_graphql_raw_text_query(api, schema):
"""Query sent as raw text body."""
api.add_route("/", GraphQLView(schema=schema, api=api))
r = api.requests.post(
"http://;/",
content=b"{ hello }",
headers={"Content-Type": "text/plain"},
)
assert r.json() == {"data": {"hello": "Hello stranger"}}
def test_graphql_invalid_variables_query_param(api, schema):
"""Invalid JSON in variables query param is treated as None."""
api.add_route("/", GraphQLView(schema=schema, api=api))
r = api.requests.get(
"http://;/?query={ hello }&variables=not-json",
headers={"Accept": "json"},
)
assert r.json() == {"data": {"hello": "Hello stranger"}}
+158
View File
@@ -0,0 +1,158 @@
"""Tests for structured logging with request context."""
import logging
import responder
from responder.ext.logging import (
LoggingMiddleware,
RequestContext,
RequestContextFilter,
get_logger,
)
def test_logging_middleware_sets_request_id():
"""LoggingMiddleware adds X-Request-ID to responses."""
api = responder.API(allowed_hosts=["localhost"], enable_logging=True)
@api.route("/")
def index(req, resp):
resp.text = "ok"
r = api.requests.get("http://localhost/")
assert r.status_code == 200
assert "x-request-id" in r.headers
assert len(r.headers["x-request-id"]) > 0
def test_logging_middleware_forwards_request_id():
"""LoggingMiddleware forwards client-provided X-Request-ID."""
api = responder.API(allowed_hosts=["localhost"], enable_logging=True)
@api.route("/")
def index(req, resp):
resp.text = "ok"
r = api.requests.get(
"http://localhost/", headers={"X-Request-ID": "custom-id-123"}
)
assert r.headers["x-request-id"] == "custom-id-123"
def test_logging_context_available_in_route():
"""Request context is available inside route handlers."""
api = responder.API(allowed_hosts=["localhost"], enable_logging=True)
captured = {}
@api.route("/ctx")
def index(req, resp):
captured["request_id"] = RequestContext.get_request_id()
captured["method"] = RequestContext.get_method()
captured["path"] = RequestContext.get_path()
captured["client_ip"] = RequestContext.get_client_ip()
resp.text = "ok"
api.requests.get("http://localhost/ctx")
assert captured["method"] == "GET"
assert captured["path"] == "/ctx"
assert captured["request_id"] != "-"
assert captured["client_ip"] != "-"
def test_logging_filter_injects_attributes():
"""RequestContextFilter adds context fields to log records."""
logger = get_logger("test.filter")
records = []
class CaptureHandler(logging.Handler):
def emit(self, record):
records.append(record)
handler = CaptureHandler()
logger.addHandler(handler)
logger.setLevel(logging.DEBUG)
api = responder.API(allowed_hosts=["localhost"], enable_logging=True)
@api.route("/log")
def index(req, resp):
logger.info("test message")
resp.text = "ok"
api.requests.get("http://localhost/log")
logger.removeHandler(handler)
assert len(records) > 0
record = records[0]
assert hasattr(record, "request_id")
assert hasattr(record, "request_method")
assert hasattr(record, "request_path")
assert hasattr(record, "client_ip")
assert record.request_method == "GET"
assert record.request_path == "/log"
def test_get_logger_avoids_duplicate_filters():
"""get_logger doesn't add duplicate filters."""
logger = get_logger("test.dedup")
count_before = sum(1 for f in logger.filters if isinstance(f, RequestContextFilter))
get_logger("test.dedup")
count_after = sum(1 for f in logger.filters if isinstance(f, RequestContextFilter))
assert count_before == count_after == 1
def test_enable_logging_supersedes_request_id():
"""enable_logging handles request IDs itself (no duplicate headers)."""
api = responder.API(
allowed_hosts=["localhost"], request_id=True, enable_logging=True
)
@api.route("/")
def index(req, resp):
resp.text = "ok"
r = api.requests.get("http://localhost/")
# Should have exactly one X-Request-ID header.
assert "x-request-id" in r.headers
def test_api_logger_attribute():
"""api.log is available when enable_logging=True."""
api = responder.API(allowed_hosts=["localhost"], enable_logging=True)
assert api.log is not None
assert api.log.name == "responder.app"
def test_api_log_always_available():
"""api.log works even without enable_logging — just no request context."""
api = responder.API(allowed_hosts=["localhost"])
assert api.log is not None
assert api.log.name == "responder.app"
api.log.info("works without enable_logging")
def test_api_logger_works_in_routes():
"""api.log can be used inside route handlers with context."""
api = responder.API(allowed_hosts=["localhost"], enable_logging=True)
records = []
class CaptureHandler(logging.Handler):
def emit(self, record):
records.append(record)
handler = CaptureHandler()
api.log.addHandler(handler)
@api.route("/")
def index(req, resp):
api.log.info("hello from route")
resp.text = "ok"
api.requests.get("http://localhost/")
api.log.removeHandler(handler)
assert any(r.msg == "hello from route" for r in records)
record = next(r for r in records if r.msg == "hello from route")
assert record.request_method == "GET"
assert record.request_path == "/"
+5 -7
View File
@@ -1,13 +1,10 @@
"""Tests for new features: validation, SSE, after_request, route groups, etc."""
import pytest
from pydantic import BaseModel
from starlette.testclient import TestClient as StarletteTestClient
import responder
from responder.ext.ratelimit import RateLimiter
# --- Pydantic auto-validation ---
@@ -42,7 +39,9 @@ def test_pydantic_request_validation():
assert "errors" in r.json()
# Invalid request — wrong type
r = api.requests.post("http://;/items", json={"name": "widget", "price": "not_a_number"})
r = api.requests.post(
"http://;/items", json={"name": "widget", "price": "not_a_number"}
)
assert r.status_code == 422
@@ -50,8 +49,7 @@ def test_pydantic_response_serialization():
"""Auto-serialize response through response_model."""
api = responder.API(allowed_hosts=[";"])
@api.route("/items", methods=["POST"],
request_model=ItemIn, response_model=ItemOut)
@api.route("/items", methods=["POST"], request_model=ItemIn, response_model=ItemOut)
async def create(req, resp):
data = await req.media()
# Include an extra field that should be stripped by the model
@@ -257,7 +255,7 @@ def test_rate_limiter():
def view(req, resp):
resp.text = "ok"
for i in range(3):
for _i in range(3):
r = api.requests.get("http://;/")
assert r.status_code == 200
assert "X-RateLimit-Remaining" in r.headers
+5 -2
View File
@@ -546,14 +546,17 @@ def test_documentation(needs_openapi):
assert "html" in r.text
def test_mount_wsgi_app(api, flask):
def test_mount_wsgi_app(flask):
# Use localhost so Werkzeug's trusted-host check accepts the request.
api = responder.API(allowed_hosts=["localhost"])
@api.route("/")
def hello(req, resp):
resp.text = "hello"
api.mount("/flask", flask)
r = api.requests.get("http://;/flask")
r = api.requests.get("http://localhost/flask")
assert r.status_code < 300