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pydantic/tests/mypy/modules/plugin_fail.py
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David Robertson 11d8589423 Teach mypy plugin that validator methods are classmethods (#4102)
* Teach mypy plugin that validator methods are classmethods

For your consideration: a patch which implements the suggestion I made here:
https://github.com/samuelcolvin/pydantic/discussions/4101

Briefly: pydantic automatically wraps validator methods using
`@classmethod`. Hence the first argument to a user-provided validator
should be `cls`. But mypy doesn't know this: it analyses validator
methods like any other regular method, believing the first parameter
`cls` to be a model instance (usually denoted self).

This means that if one annotates `cls` as `Type[...]` then mypy
believes raises an error:

	error: The erased type of self "Type[temp.Model]" is not a supertype of its class "temp.Model"

I concede that this is an extremely niche thing. The only tangible
end-user benefit I can think of is that it'll stop you from calling
instance methods in a validator.

----

I haven't written a mypy plugin before, so this is a bit of a
hack-until-it-works. But it was more straightforward than I expected to
get something working!

* changelog

* Add failure test
2022-08-09 17:04:05 +01:00

265 lines
4.8 KiB
Python

from typing import Any, Generic, List, Optional, Set, TypeVar, Union
from pydantic import BaseModel, BaseSettings, Extra, Field, validator
from pydantic.dataclasses import dataclass
from pydantic.generics import GenericModel
class Model(BaseModel):
x: int
y: str
def method(self) -> None:
pass
class Config:
alias_generator = None
allow_mutation = False
extra = Extra.forbid
def config_method(self) -> None:
...
model = Model(x=1, y='y', z='z')
model = Model(x=1)
model.y = 'a'
Model.from_orm({})
Model.from_orm({}) # type: ignore[pydantic-orm] # noqa F821
class ForbidExtraModel(BaseModel):
class Config:
extra = 'forbid'
ForbidExtraModel(x=1)
class ForbidExtraModel2(BaseModel):
class Config:
extra = 'forbid'
validate_all = False
Config.validate_all = True
ForbidExtraModel2(x=1)
class BadExtraModel(BaseModel):
class Config:
extra = 1 # type: ignore[pydantic-config] # noqa F821
extra = 1
class BadConfig1(BaseModel):
class Config:
orm_mode: Any = {} # not sensible, but should still be handled gracefully
class BadConfig2(BaseModel):
class Config:
orm_mode = list # not sensible, but should still be handled gracefully
class InheritingModel(Model):
class Config:
allow_mutation = True
class DefaultTestingModel(BaseModel):
# Required
a: int
b: int = ...
c: int = Field(...)
d: Union[int, str]
e = ...
# Not required
f: Optional[int]
g: int = 1
h: int = Field(1)
i: int = Field(None)
j = 1
DefaultTestingModel()
class UndefinedAnnotationModel(BaseModel):
undefined: Undefined # noqa F821
UndefinedAnnotationModel()
class Settings(BaseSettings):
x: int
Model.construct(x=1)
Model.construct(_fields_set={'x'}, x=1, y='2')
Model.construct(x='1', y='2')
Settings() # should pass here due to possibly reading from environment
# Strict mode fails
inheriting = InheritingModel(x='1', y='1')
Settings(x='1')
Model(x='1', y='2')
class Blah(BaseModel):
fields_set: Optional[Set[str]] = None
# (comment to keep line numbers unchanged)
T = TypeVar('T')
class Response(GenericModel, Generic[T]):
data: T
error: Optional[str]
response = Response[Model](data=model, error=None)
response = Response[Model](data=1, error=None)
class AliasModel(BaseModel):
x: str = Field(..., alias='y')
z: int
AliasModel(y=1, z=2)
x_alias = 'y'
class DynamicAliasModel(BaseModel):
x: str = Field(..., alias=x_alias)
z: int
DynamicAliasModel(y='y', z='1')
class DynamicAliasModel2(BaseModel):
x: str = Field(..., alias=x_alias)
z: int
class Config:
allow_population_by_field_name = True
DynamicAliasModel2(y='y', z=1)
DynamicAliasModel2(x='y', z=1)
class AliasGeneratorModel(BaseModel):
x: int
class Config:
alias_generator = lambda x: x + '_' # noqa E731
AliasGeneratorModel(x=1)
AliasGeneratorModel(x_=1)
AliasGeneratorModel(z=1)
class AliasGeneratorModel2(BaseModel):
x: int = Field(..., alias='y')
class Config: # type: ignore[pydantic-alias] # noqa F821
alias_generator = lambda x: x + '_' # noqa E731
class UntypedFieldModel(BaseModel):
x: int = 1
y = 2
z = 2 # type: ignore[pydantic-field] # noqa F821
AliasGeneratorModel2(x=1)
AliasGeneratorModel2(y=1, z=1)
class CoverageTester(Missing): # noqa F821
def from_orm(self) -> None:
pass
CoverageTester().from_orm()
@dataclass(config={})
class AddProject:
name: str
slug: Optional[str]
description: Optional[str]
p = AddProject(name='x', slug='y', description='z')
# Same as Model, but with frozen = True
class FrozenModel(BaseModel):
x: int
y: str
class Config:
alias_generator = None
frozen = True
extra = Extra.forbid
frozenmodel = FrozenModel(x=1, y='b')
frozenmodel.y = 'a'
class InheritingModel2(FrozenModel):
class Config:
frozen = False
inheriting2 = InheritingModel2(x=1, y='c')
inheriting2.y = 'd'
def _default_factory() -> str:
...
test: List[str] = []
class FieldDefaultTestingModel(BaseModel):
# Default
e: int = Field(None)
f: int = None
# Default factory
g: str = Field(default_factory=set)
h: int = Field(default_factory=_default_factory)
i: List[int] = Field(default_factory=list)
l: str = Field(default_factory=3)
# Default and default factory
m: int = Field(default=1, default_factory=list)
class ModelWithAnnotatedValidator(BaseModel):
name: str
@validator('name')
def noop_validator_with_annotations(self, name: str) -> str:
# This is a mistake: the first argument to a validator is the class itself,
# like a classmethod.
self.instance_method()
return name
def instance_method(self) -> None:
...