Validate Field(validators=[...]) more precisely

django-stubs/contrib/gis/db/models/fields.pyi

@@ -66,7 +66,7 @@ class BaseSpatialField(Field[_ST, _GT]):
         db_column: str | None = ...,
         db_comment: str | None = ...,
         db_tablespace: str | None = ...,
-        validators: Iterable[_ValidatorCallable] = ...,
+        validators: Iterable[_ValidatorCallable[_GT]] = ...,
         error_messages: _ErrorMessagesMapping | None = ...,
     ) -> None: ...
     @override
@@ -115,7 +115,7 @@ class GeometryField(BaseSpatialField[_ST, _GT]):
         db_column: str | None = ...,
         db_comment: str | None = ...,
         db_tablespace: str | None = ...,
-        validators: Iterable[_ValidatorCallable] = ...,
+        validators: Iterable[_ValidatorCallable[_GT]] = ...,
         error_messages: _ErrorMessagesMapping | None = ...,
     ) -> None: ...
     @override

django-stubs/contrib/postgres/fields/array.pyi

@@ -28,7 +28,7 @@ class ArrayField(CheckPostgresInstalledMixin, CheckFieldDefaultMixin, Field[_ST,
     default_error_messages: ClassVar[_ErrorMessagesDict]
     base_field: Field
     size: int | None
-    default_validators: Sequence[_ValidatorCallable]
+    default_validators: Sequence[_ValidatorCallable[_GT]]
     from_db_value: Any
     def __init__(
         self,
@@ -56,7 +56,7 @@ class ArrayField(CheckPostgresInstalledMixin, CheckFieldDefaultMixin, Field[_ST,
         db_column: str | None = ...,
         db_comment: str | None = ...,
         db_tablespace: str | None = ...,
-        validators: Iterable[_ValidatorCallable] = ...,
+        validators: Iterable[_ValidatorCallable[_GT]] = ...,
         error_messages: _ErrorMessagesMapping | None = ...,
     ) -> None: ...
     @override

django-stubs/core/validators.pyi

@@ -1,7 +1,7 @@
 from collections.abc import Callable, Collection, Sequence, Sized
 from decimal import Decimal
 from re import Pattern, RegexFlag
-from typing import Any, TypeAlias
+from typing import Any, TypeAlias, TypeVar
 
 from django.core.files.base import File
 from django.utils.deconstruct import _Deconstructible
@@ -12,7 +12,9 @@ EMPTY_VALUES: Any
 
 _Regex: TypeAlias = str | Pattern[str]
 
-_ValidatorCallable: TypeAlias = Callable[[Any], None]  # noqa: PYI047
+_VT = TypeVar("_VT", contravariant=True)
+
+_ValidatorCallable: TypeAlias = Callable[[_VT], None]  # noqa: PYI047
 
 class RegexValidator(_Deconstructible):
     regex: _Regex  # Pattern[str] on instance, but may be str on class definition

django-stubs/db/models/fields/__init__.pyi

@@ -144,7 +144,7 @@ class Field(RegisterLookupMixin, Generic[_ST, _GT]):
     empty_values: Sequence[Any]
     creation_counter: int
     auto_creation_counter: int
-    default_validators: Sequence[validators._ValidatorCallable]
+    default_validators: Sequence[validators._ValidatorCallable[_GT]]
     default_error_messages: ClassVar[_ErrorMessagesDict]
     hidden: bool
     system_check_removed_details: Any | None
@@ -172,7 +172,7 @@ class Field(RegisterLookupMixin, Generic[_ST, _GT]):
         db_column: str | None = None,
         db_tablespace: str | None = None,
         auto_created: bool = False,
-        validators: Iterable[validators._ValidatorCallable] = (),
+        validators: Iterable[validators._ValidatorCallable[_GT]] = (),
         error_messages: _ErrorMessagesMapping | None = None,
         db_comment: str | None = None,
         db_default: type[NOT_PROVIDED] | Expression | _ST = ...,
@@ -205,7 +205,7 @@ class Field(RegisterLookupMixin, Generic[_ST, _GT]):
     @cached_property
     def error_messages(self) -> _ErrorMessagesDict: ...
     @cached_property
-    def validators(self) -> list[validators._ValidatorCallable]: ...
+    def validators(self) -> list[validators._ValidatorCallable[_GT]]: ...
     def run_validators(self, value: Any) -> None: ...
     def validate(self, value: Any, model_instance: Model | None) -> None: ...
     def clean(self, value: Any, model_instance: Model | None) -> Any: ...
@@ -325,7 +325,7 @@ class DecimalField(Field[_ST, _GT]):
         db_column: str | None = ...,
         db_comment: str | None = ...,
         db_tablespace: str | None = ...,
-        validators: Iterable[validators._ValidatorCallable] = ...,
+        validators: Iterable[validators._ValidatorCallable[_GT]] = ...,
         error_messages: _ErrorMessagesMapping | None = ...,
     ) -> None: ...
     @cached_property
@@ -361,7 +361,7 @@ class CharField(Field[_ST, _GT]):
         db_column: str | None = ...,
         db_comment: str | None = ...,
         db_tablespace: str | None = ...,
-        validators: Iterable[validators._ValidatorCallable] = ...,
+        validators: Iterable[validators._ValidatorCallable[_GT]] = ...,
         error_messages: _ErrorMessagesMapping | None = ...,
         *,
         db_collation: str | None = None,
@@ -393,7 +393,7 @@ class SlugField(CharField[_ST, _GT]):
         db_column: str | None = ...,
         db_comment: str | None = ...,
         db_tablespace: str | None = ...,
-        validators: Iterable[validators._ValidatorCallable] = ...,
+        validators: Iterable[validators._ValidatorCallable[_GT]] = ...,
         error_messages: _ErrorMessagesMapping | None = ...,
         *,
         max_length: int | None = 50,
@@ -434,7 +434,7 @@ class URLField(CharField[_ST, _GT]):
         db_comment: str | None = ...,
         db_tablespace: str | None = ...,
         auto_created: bool = ...,
-        validators: Iterable[validators._ValidatorCallable] = ...,
+        validators: Iterable[validators._ValidatorCallable[_GT]] = ...,
         error_messages: _ErrorMessagesMapping | None = ...,
     ) -> None: ...
     @override
@@ -468,7 +468,7 @@ class TextField(Field[_ST, _GT]):
         db_column: str | None = ...,
         db_comment: str | None = ...,
         db_tablespace: str | None = ...,
-        validators: Iterable[validators._ValidatorCallable] = ...,
+        validators: Iterable[validators._ValidatorCallable[_GT]] = ...,
         error_messages: _ErrorMessagesMapping | None = ...,
         *,
         db_collation: str | None = None,
@@ -520,7 +520,7 @@ class GenericIPAddressField(Field[_ST, _GT]):
         db_column: str | None = ...,
         db_comment: str | None = ...,
         db_tablespace: str | None = ...,
-        validators: Iterable[validators._ValidatorCallable] = ...,
+        validators: Iterable[validators._ValidatorCallable[_GT]] = ...,
         error_messages: _ErrorMessagesMapping | None = ...,
     ) -> None: ...
     @override
@@ -558,7 +558,7 @@ class DateField(DateTimeCheckMixin, Field[_ST, _GT]):
         db_column: str | None = ...,
         db_comment: str | None = ...,
         db_tablespace: str | None = ...,
-        validators: Iterable[validators._ValidatorCallable] = ...,
+        validators: Iterable[validators._ValidatorCallable[_GT]] = ...,
         error_messages: _ErrorMessagesMapping | None = ...,
     ) -> None: ...
     @override
@@ -593,7 +593,7 @@ class TimeField(DateTimeCheckMixin, Field[_ST, _GT]):
         db_column: str | None = ...,
         db_comment: str | None = ...,
         db_tablespace: str | None = ...,
-        validators: Iterable[validators._ValidatorCallable] = ...,
+        validators: Iterable[validators._ValidatorCallable[_GT]] = ...,
         error_messages: _ErrorMessagesMapping | None = ...,
     ) -> None: ...
     @override
@@ -635,7 +635,7 @@ class UUIDField(Field[_ST, _GT]):
         db_comment: str | None = ...,
         db_tablespace: str | None = ...,
         auto_created: bool = ...,
-        validators: Iterable[validators._ValidatorCallable] = ...,
+        validators: Iterable[validators._ValidatorCallable[_GT]] = ...,
         error_messages: _ErrorMessagesMapping | None = ...,
     ) -> None: ...
     @override
@@ -673,7 +673,7 @@ class FilePathField(Field[_ST, _GT]):
         db_column: str | None = ...,
         db_comment: str | None = ...,
         db_tablespace: str | None = ...,
-        validators: Iterable[validators._ValidatorCallable] = ...,
+        validators: Iterable[validators._ValidatorCallable[_GT]] = ...,
         error_messages: _ErrorMessagesMapping | None = ...,
     ) -> None: ...
     @override

django-stubs/db/models/fields/composite.pyi

@@ -47,7 +47,7 @@ class CompositePrimaryKey(Field[Any, Any]):
         db_column: None = None,
         db_tablespace: str | None = None,
         auto_created: bool = False,
-        validators: Iterable[validators._ValidatorCallable] = (),
+        validators: Iterable[validators._ValidatorCallable[Any]] = (),
         error_messages: Mapping[str, _StrOrPromise] | None = None,
         db_comment: str | None = None,
         db_default: type[NOT_PROVIDED] = ...,

django-stubs/db/models/fields/files.pyi

@@ -90,7 +90,7 @@ class FileField(Field[Any, Any]):
         db_column: str | None = ...,
         db_comment: str | None = ...,
         db_tablespace: str | None = ...,
-        validators: Iterable[validators._ValidatorCallable] = ...,
+        validators: Iterable[validators._ValidatorCallable[Any]] = ...,
         error_messages: _ErrorMessagesMapping | None = ...,
     ) -> None: ...
     # class access

django-stubs/db/models/fields/generated.pyi

@@ -42,7 +42,7 @@ class GeneratedField(models.Field[Any, Any]):
         db_column: str | None = ...,
         db_comment: str | None = ...,
         db_tablespace: str | None = ...,
-        validators: Iterable[_ValidatorCallable] = ...,
+        validators: Iterable[_ValidatorCallable[Any]] = ...,
         error_messages: _ErrorMessagesMapping | None = ...,
         **kwargs: Any,
     ) -> None: ...

django-stubs/db/models/fields/related.pyi

@@ -73,7 +73,7 @@ class RelatedField(FieldCacheMixin, Field[_ST, _GT]):
         db_column: str | None = ...,
         db_tablespace: str | None = ...,
         auto_created: bool = ...,
-        validators: Iterable[validators._ValidatorCallable] = ...,
+        validators: Iterable[validators._ValidatorCallable[_GT]] = ...,
         error_messages: _ErrorMessagesMapping | None = ...,
         db_comment: str | None = ...,
     ) -> None: ...
@@ -129,7 +129,7 @@ class ForeignObject(RelatedField[_ST, _GT]):
         help_text: _StrOrPromise = ...,
         db_column: str | None = ...,
         db_tablespace: str | None = ...,
-        validators: Iterable[validators._ValidatorCallable] = ...,
+        validators: Iterable[validators._ValidatorCallable[_GT]] = ...,
         error_messages: _ErrorMessagesMapping | None = ...,
         db_comment: str | None = ...,
     ) -> None: ...
@@ -212,7 +212,7 @@ class ForeignKey(ForeignObject[_ST, _GT]):
         help_text: _StrOrPromise = ...,
         db_column: str | None = ...,
         db_tablespace: str | None = ...,
-        validators: Iterable[validators._ValidatorCallable] = ...,
+        validators: Iterable[validators._ValidatorCallable[_GT]] = ...,
         error_messages: _ErrorMessagesMapping | None = ...,
         db_comment: str | None = ...,
     ) -> None: ...
@@ -264,7 +264,7 @@ class OneToOneField(ForeignKey[_ST, _GT]):
         help_text: _StrOrPromise = ...,
         db_column: str | None = ...,
         db_tablespace: str | None = ...,
-        validators: Iterable[validators._ValidatorCallable] = ...,
+        validators: Iterable[validators._ValidatorCallable[_GT]] = ...,
         error_messages: _ErrorMessagesMapping | None = ...,
         db_comment: str | None = ...,
     ) -> None: ...

tests/assert_type/db/models/fields/test_validators.py

@@ -0,0 +1,35 @@
+from collections.abc import Callable
+from datetime import date
+from decimal import Decimal
+
+from django.db import models
+from django.db.models.expressions import Combinable
+from typing_extensions import assert_type
+
+
+def validate_title(value: str) -> None: ...
+
+
+def validate_price(value: Decimal) -> None: ...
+
+
+def validate_published_on(value: date) -> None: ...
+
+
+title_field: models.CharField[str | int | Combinable, str] = models.CharField(
+    max_length=200,
+    validators=[validate_title],
+)
+price_field: models.DecimalField[str | float | Decimal | Combinable, Decimal] = models.DecimalField(
+    max_digits=8,
+    decimal_places=2,
+    validators=[validate_price],
+)
+published_on_field: models.DateField[str | date | Combinable, date] = models.DateField(
+    validators=[validate_published_on],
+)
+
+
+assert_type(title_field.validators, list[Callable[[str], None]])  # ty: ignore[type-assertion-failure]
+assert_type(price_field.validators, list[Callable[[Decimal], None]])  # ty: ignore[type-assertion-failure]
+assert_type(published_on_field.validators, list[Callable[[date], None]])  # ty: ignore[type-assertion-failure]

tests/typecheck/fields/test_validators.yml

@@ -0,0 +1,46 @@
+-   case: model_field_validators_follow_get_type_and_support_subclassing
+    main: |
+        from datetime import date
+        from decimal import Decimal
+        from typing import NewType
+        from uuid import UUID
+
+        from django.db import models
+        from django.db.models.expressions import Combinable
+        from typing_extensions import reveal_type
+
+        SlugValue = NewType("SlugValue", str)
+
+        class CustomSlugField(models.SlugField[SlugValue | str | int | Combinable, SlugValue]):
+            ...
+
+        def validate_slug(value: str) -> None: ...
+        def validate_price(value: Decimal) -> None: ...
+        def validate_published_on(value: date) -> None: ...
+        def validate_identifier(value: UUID) -> None: ...
+        def validate_ip(value: str) -> None: ...
+        def validate_custom_slug(value: SlugValue) -> None: ...
+        def validate_int(value: int) -> None: ...
+        def validate_date(value: date) -> None: ...
+        def validate_uuid(value: UUID) -> None: ...
+
+        class Article(models.Model):
+            slug = models.SlugField(validators=[validate_slug])
+            price = models.DecimalField(max_digits=8, decimal_places=2, validators=[validate_price])
+            published_on = models.DateField(validators=[validate_published_on])
+            identifier = models.UUIDField(validators=[validate_identifier])
+            ip_address = models.GenericIPAddressField(validators=[validate_ip])
+            custom_slug = CustomSlugField(validators=[validate_custom_slug])
+
+            bad_slug = models.SlugField(validators=[validate_int])  # E: List item 0 has incompatible type "Callable[[int], None]"; expected "Callable[[str], None]"  [list-item]
+            bad_published_on = models.DateField(validators=[validate_int])  # E: List item 0 has incompatible type "Callable[[int], None]"; expected "Callable[[date], None]"  [list-item]
+            bad_identifier = models.UUIDField(validators=[validate_date])  # E: List item 0 has incompatible type "Callable[[date], None]"; expected "Callable[[UUID], None]"  [list-item]
+            bad_ip_address = models.GenericIPAddressField(validators=[validate_uuid])  # E: List item 0 has incompatible type "Callable[[UUID], None]"; expected "Callable[[str], None]"  [list-item]
+            bad_price = models.DecimalField(max_digits=8, decimal_places=2, validators=[validate_uuid])  # E: List item 0 has incompatible type "Callable[[UUID], None]"; expected "Callable[[Decimal], None]"  [list-item]
+
+        reveal_type(Article().slug)  # N: Revealed type is "builtins.str"
+        reveal_type(Article().price)  # N: Revealed type is "decimal.Decimal"
+        reveal_type(Article().published_on)  # N: Revealed type is "datetime.date"
+        reveal_type(Article().identifier)  # N: Revealed type is "uuid.UUID"
+        reveal_type(Article().ip_address)  # N: Revealed type is "builtins.str"
+        reveal_type(Article().custom_slug)  # N: Revealed type is "main.SlugValue"