add support for _meta.get_field() typechecking

django-stubs/core/serializers/base.pyi

@@ -1,13 +1,13 @@
-from collections import OrderedDict
 from datetime import date
 from io import BufferedReader, StringIO, TextIOWrapper
-from typing import Any, Dict, Iterator, List, Optional, Tuple, Type, Union
+from typing import Any, Dict, Iterable, List, Mapping, Optional, Type, Union
 from uuid import UUID
 
 from django.core.management.base import OutputWrapper
 from django.db.models.base import Model
 from django.db.models.fields.related import ForeignKey, ManyToManyField
-from django.db.models.query import QuerySet
+
+from django.db.models.fields import Field
 
 class SerializerDoesNotExist(KeyError): ...
 class SerializationError(Exception): ...
@@ -43,7 +43,7 @@ class Serializer:
     first: bool = ...
     def serialize(
         self,
-        queryset: Union[Iterator[Any], List[Model], QuerySet],
+        queryset: Iterable[Model],
         *,
         stream: Optional[Any] = ...,
         fields: Optional[Any] = ...,
@@ -52,7 +52,7 @@ class Serializer:
         progress_output: Optional[Any] = ...,
         object_count: int = ...,
         **options: Any
-    ) -> Optional[Union[List[OrderedDict], bytes, str]]: ...
+    ) -> Any: ...
     def start_serialization(self) -> None: ...
     def end_serialization(self) -> None: ...
     def start_object(self, obj: Any) -> None: ...
@@ -72,13 +72,16 @@ class Deserializer:
 class DeserializedObject:
     object: Any = ...
     m2m_data: Dict[str, List[int]] = ...
-    def __init__(self, obj: Model, m2m_data: Optional[Dict[str, List[int]]] = ...) -> None: ...
+    deferred_fields: Mapping[Field, Any]
+    def __init__(
+        self,
+        obj: Model,
+        m2m_data: Optional[Dict[str, List[int]]] = ...,
+        deferred_fields: Optional[Mapping[Field, Any]] = ...,
+    ) -> None: ...
     def save(self, save_m2m: bool = ..., using: Optional[str] = ..., **kwargs: Any) -> None: ...
+    def save_deferred_fields(self, using: Optional[str] = ...) -> None: ...
 
 def build_instance(Model: Type[Model], data: Dict[str, Optional[Union[date, int, str, UUID]]], db: str) -> Model: ...
-def deserialize_m2m_values(
+def deserialize_m2m_values(field: ManyToManyField, field_value: Any, using: str) -> List[Any]: ...
-    field: ManyToManyField, field_value: Union[List[List[str]], List[int]], using: str
+def deserialize_fk_value(field: ForeignKey, field_value: Any, using: str) -> Any: ...
-) -> List[int]: ...
-def deserialize_fk_value(
-    field: ForeignKey, field_value: Optional[Union[List[str], Tuple[str], int, str]], using: str
-) -> Optional[Union[int, str, UUID]]: ...

django-stubs/db/models/base.pyi

@@ -1,4 +1,4 @@
-from typing import Any, Dict, List, Optional, Sequence, Set, Tuple, TypeVar, Union, ClassVar
+from typing import Any, Dict, List, Optional, Sequence, Set, Tuple, TypeVar, Union, ClassVar, Type
 
 from django.db.models.manager import Manager
 
@@ -6,16 +6,16 @@ from django.core.checks.messages import CheckMessage
 
 from django.db.models.options import Options
 
-class ModelBase(type): ...
-
 _Self = TypeVar("_Self", bound="Model")
 
+class ModelBase(type): ...
+
 class Model(metaclass=ModelBase):
     class DoesNotExist(Exception): ...
     class MultipleObjectsReturned(Exception): ...
     class Meta: ...
-    _meta: Options
     _default_manager: Manager[Model]
+    _meta: Options[Any]
     pk: Any = ...
     def __init__(self: _Self, *args, **kwargs) -> None: ...
     def delete(self, using: Any = ..., keep_parents: bool = ...) -> Tuple[int, Dict[str, int]]: ...

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

@@ -39,12 +39,14 @@ class Field(RegisterLookupMixin, Generic[_ST, _GT]):
     max_length: Optional[int]
     model: Type[Model]
     name: str
+    verbose_name: str
     blank: bool = ...
     null: bool = ...
     editable: bool = ...
     choices: Optional[_FieldChoices] = ...
     db_column: Optional[str]
     column: str
+    error_messages: _ErrorMessagesToOverride
     def __init__(
         self,
         verbose_name: Optional[Union[str, bytes]] = ...,
@@ -78,6 +80,7 @@ class Field(RegisterLookupMixin, Generic[_ST, _GT]):
     def get_prep_value(self, value: Any) -> Any: ...
     def get_internal_type(self) -> str: ...
     def formfield(self, **kwargs) -> FormField: ...
+    def save_form_data(self, instance: Model, data: Any) -> None: ...
     def contribute_to_class(self, cls: Type[Model], name: str, private_only: bool = ...) -> None: ...
     def to_python(self, value: Any) -> Any: ...
     def clean(self, value: Any, model_instance: Optional[Model]) -> Any: ...
@@ -91,6 +94,8 @@ class Field(RegisterLookupMixin, Generic[_ST, _GT]):
     def has_default(self) -> bool: ...
     def get_default(self) -> Any: ...
     def check(self, **kwargs: Any) -> List[checks.Error]: ...
+    @property
+    def validators(self) -> List[_ValidatorCallable]: ...
 
 class IntegerField(Field[_ST, _GT]):
     _pyi_private_set_type: Union[float, int, str, Combinable]

django-stubs/db/models/options.pyi

@@ -1,5 +1,5 @@
 import collections
-from typing import Any, Callable, Dict, Iterator, List, Optional, Set, Tuple, Type, Union
+from typing import Any, Callable, Dict, Iterator, List, Optional, Set, Tuple, Type, Union, TypeVar, Generic
 
 from django.apps.config import AppConfig
 from django.apps.registry import Apps
@@ -29,7 +29,9 @@ def make_immutable_fields_list(
     name: str, data: Union[Iterator[Any], List[Union[ArrayField, CIText]], List[Union[Field, FieldCacheMixin]]]
 ) -> ImmutableList: ...
 
-class Options:
+_M = TypeVar('_M', bound=Model)
+
+class Options(Generic[_M]):
     base_manager: Manager
     concrete_fields: ImmutableList
     default_manager: Manager

django-stubs/db/models/query.pyi

@@ -78,7 +78,7 @@ class QuerySet(Generic[_T, _Row], Collection[_Row], Sized):
     def iterator(self, chunk_size: int = ...) -> Iterator[_Row]: ...
     def aggregate(self, *args: Any, **kwargs: Any) -> Dict[str, Any]: ...
     def get(self, *args: Any, **kwargs: Any) -> _Row: ...
-    def create(self, **kwargs: Any) -> _T: ...
+    def create(self, *args: Any, **kwargs: Any) -> _T: ...
     def bulk_create(
         self, objs: Iterable[Model], batch_size: Optional[int] = ..., ignore_conflicts: bool = ...
     ) -> List[_T]: ...

mypy_django_plugin/lib/fullnames.py

@@ -35,3 +35,4 @@ RELATED_FIELDS_CLASSES = {
 }
 
 MIGRATION_CLASS_FULLNAME = 'django.db.migrations.migration.Migration'
+OPTIONS_CLASS_FULLNAME = 'django.db.models.options.Options'

mypy_django_plugin/main.py

@@ -11,7 +11,7 @@ from mypy.types import Type as MypyType
 
 from mypy_django_plugin.django.context import DjangoContext
 from mypy_django_plugin.lib import fullnames, helpers
-from mypy_django_plugin.transformers import fields, forms, init_create, querysets, settings
+from mypy_django_plugin.transformers import fields, forms, init_create, querysets, settings, meta
 from mypy_django_plugin.transformers.models import process_model_class
 
 
@@ -168,15 +168,20 @@ class NewSemanalDjangoPlugin(Plugin):
                 return forms.extract_proper_type_for_get_form
 
         if method_name == 'values':
-            model_info = self._get_typeinfo_or_none(class_fullname)
+            info = self._get_typeinfo_or_none(class_fullname)
-            if model_info and model_info.has_base(fullnames.QUERYSET_CLASS_FULLNAME):
+            if info and info.has_base(fullnames.QUERYSET_CLASS_FULLNAME):
                 return partial(querysets.extract_proper_type_queryset_values, django_context=self.django_context)
 
         if method_name == 'values_list':
-            model_info = self._get_typeinfo_or_none(class_fullname)
+            info = self._get_typeinfo_or_none(class_fullname)
-            if model_info and model_info.has_base(fullnames.QUERYSET_CLASS_FULLNAME):
+            if info and info.has_base(fullnames.QUERYSET_CLASS_FULLNAME):
                 return partial(querysets.extract_proper_type_queryset_values_list, django_context=self.django_context)
 
+        if method_name == 'get_field':
+            info = self._get_typeinfo_or_none(class_fullname)
+            if info and info.has_base(fullnames.OPTIONS_CLASS_FULLNAME):
+                return partial(meta.return_proper_field_type_from_get_field, django_context=self.django_context)
+
         manager_classes = self._get_current_manager_bases()
         if class_fullname in manager_classes and method_name == 'create':
             return partial(init_create.redefine_and_typecheck_model_create, django_context=self.django_context)

mypy_django_plugin/transformers/meta.py

@@ -0,0 +1,38 @@
+from django.core.exceptions import FieldDoesNotExist
+from mypy.plugin import MethodContext
+from mypy.types import AnyType, Type as MypyType, TypeOfAny, Instance
+
+from mypy_django_plugin.django.context import DjangoContext
+from mypy_django_plugin.lib import fullnames, helpers
+
+
+def _get_field_instance(ctx: MethodContext, field_fullname: str) -> MypyType:
+    field_info = helpers.lookup_fully_qualified_typeinfo(ctx.api, field_fullname)
+    return Instance(field_info, [AnyType(TypeOfAny.explicit), AnyType(TypeOfAny.explicit)])
+
+
+def return_proper_field_type_from_get_field(ctx: MethodContext, django_context: DjangoContext) -> MypyType:
+    model_type = ctx.type.args[0]
+    if not isinstance(model_type, Instance):
+        return _get_field_instance(ctx, fullnames.FIELD_FULLNAME)
+
+    model_cls = django_context.get_model_class_by_fullname(model_type.type.fullname())
+    if model_cls is None:
+        return _get_field_instance(ctx, fullnames.FIELD_FULLNAME)
+
+    field_name_expr = helpers.get_call_argument_by_name(ctx, 'field_name')
+    if field_name_expr is None:
+        return _get_field_instance(ctx, fullnames.FIELD_FULLNAME)
+
+    field_name = helpers.resolve_string_attribute_value(field_name_expr, ctx, django_context)
+    if field_name is None:
+        return _get_field_instance(ctx, fullnames.FIELD_FULLNAME)
+
+    try:
+        field = model_cls._meta.get_field(field_name)
+    except FieldDoesNotExist as exc:
+        ctx.api.fail(exc.args[0], ctx.context)
+        return AnyType(TypeOfAny.from_error)
+
+    field_fullname = helpers.get_class_fullname(field.__class__)
+    return _get_field_instance(ctx, field_fullname)

mypy_django_plugin/transformers/models.py

@@ -2,15 +2,15 @@ from abc import ABCMeta, abstractmethod
 from abc import ABCMeta, abstractmethod
 from typing import cast
 
-from django.db.models.fields import DateTimeField, DateField
 from django.db.models.fields.related import ForeignKey
 from django.db.models.fields.reverse_related import ManyToManyRel, ManyToOneRel, OneToOneRel
 from mypy.newsemanal.semanal import NewSemanticAnalyzer
-from mypy.nodes import MDEF, SymbolTableNode, TypeInfo, Var, Argument, ARG_NAMED_OPT, ARG_STAR2
+from mypy.nodes import ARG_STAR2, Argument, MDEF, SymbolTableNode, TypeInfo, Var
 from mypy.plugin import ClassDefContext
 from mypy.plugins import common
-from mypy.types import Instance, TypeOfAny, AnyType
+from mypy.types import AnyType, Instance, TypeOfAny
 
+from django.db.models.fields import DateField, DateTimeField
 from mypy_django_plugin.django.context import DjangoContext
 from mypy_django_plugin.lib import fullnames, helpers
 from mypy_django_plugin.transformers import fields
@@ -177,6 +177,15 @@ class AddExtraFieldMethods(ModelClassInitializer):
                                   return_type=return_type)
 
 
+class AddMetaOptionsAttribute(ModelClassInitializer):
+    def run(self):
+        if '_meta' not in self.model_classdef.info.names:
+            options_info = self.lookup_typeinfo_or_incomplete_defn_error(fullnames.OPTIONS_CLASS_FULLNAME)
+            self.add_new_node_to_model_class('_meta',
+                                             Instance(options_info, [
+                                                 Instance(self.model_classdef.info, [])
+                                             ]))
+
 
 def process_model_class(ctx: ClassDefContext,
                         django_context: DjangoContext) -> None:
@@ -186,6 +195,7 @@ def process_model_class(ctx: ClassDefContext,
         AddRelatedModelsId,
         AddManagers,
         AddExtraFieldMethods,
+        AddMetaOptionsAttribute
     ]
     for initializer_cls in initializers:
         try:

test-data/typecheck/models/test_meta_options.yml

@@ -0,0 +1,33 @@
+-   case: meta_attribute_has_a_type_of_current_model
+    main: |
+        from myapp.models import MyUser
+        reveal_type(MyUser._meta)  # N: Revealed type is 'django.db.models.options.Options[myapp.models.MyUser]'
+    installed_apps:
+        - myapp
+    files:
+        -   path: myapp/__init__.py
+        -   path: myapp/models.py
+            content: |
+                from django.db import models
+                class MyUser(models.Model):
+                    pass
+
+-   case: get_field_returns_proper_field_type
+    main: |
+        from myapp.models import MyUser
+        reveal_type(MyUser._meta.get_field('name'))  # N: Revealed type is 'django.db.models.fields.CharField[Any, Any]'
+        reveal_type(MyUser._meta.get_field('age'))  # N: Revealed type is 'django.db.models.fields.IntegerField[Any, Any]'
+        reveal_type(MyUser._meta.get_field('unknown'))
+    out: |
+        main:4: note: Revealed type is 'Any'
+        main:4: error: MyUser has no field named 'unknown'
+    installed_apps:
+        - myapp
+    files:
+        -   path: myapp/__init__.py
+        -   path: myapp/models.py
+            content: |
+                from django.db import models
+                class MyUser(models.Model):
+                    name = models.CharField(max_length=100)
+                    age = models.IntegerField()