pydantic/docs/usage/mypy.md

Pydantic works with mypy provided you use the annotation-only version of required fields:

{!./examples/mypy.py!}

(This script is complete, it should run "as is")

You can also run it through mypy with:

mypy \
  --ignore-missing-imports \
  --follow-imports=skip \
  --strict-optional \
  pydantic_mypy_test.py

Strict Optional

For your code to pass with --strict-optional, you need to to use Optional[] or an alias of Optional[] for all fields with None as the default. (This is standard with mypy.)

Pydantic provides a few useful optional or union types:

• NoneStr aka. Optional[str]
• NoneBytes aka. Optional[bytes]
• StrBytes aka. Union[str, bytes]
• NoneStrBytes aka. Optional[StrBytes]

If these aren't sufficient you can of course define your own.