add nested Meta inheritance support for forms

mypy_django_plugin/helpers.py

@@ -22,6 +22,7 @@ QUERYSET_CLASS_FULLNAME = 'django.db.models.query.QuerySet'
 BASE_MANAGER_CLASS_FULLNAME = 'django.db.models.manager.BaseManager'
 MANAGER_CLASS_FULLNAME = 'django.db.models.manager.Manager'
 RELATED_MANAGER_CLASS_FULLNAME = 'django.db.models.manager.RelatedManager'
+MODELFORM_CLASS_FULLNAME = 'django.forms.models.ModelForm'
 
 MANAGER_CLASSES = {
     MANAGER_CLASS_FULLNAME,
@@ -273,3 +274,10 @@ def has_any_of_bases(info: TypeInfo, bases: typing.Sequence[str]) -> bool:
 
 def is_none_expr(expr: Expression) -> bool:
     return isinstance(expr, NameExpr) and expr.fullname == 'builtins.None'
+
+
+def get_nested_meta_node_for_current_class(info: TypeInfo) -> Optional[TypeInfo]:
+    metaclass_sym = info.names.get('Meta')
+    if metaclass_sym is not None and isinstance(metaclass_sym.node, TypeInfo):
+        return metaclass_sym.node
+    return None

mypy_django_plugin/main.py

@@ -1,5 +1,5 @@
 import os
-from typing import Callable, Dict, Optional, Union, cast
+from typing import Callable, Optional, Set, Union, cast, Dict
 
 from mypy.checker import TypeChecker
 from mypy.nodes import MemberExpr, TypeInfo
@@ -9,6 +9,7 @@ from mypy.types import AnyType, Instance, Type, TypeOfAny, TypeType, UnionType
 from mypy_django_plugin import helpers, monkeypatch
 from mypy_django_plugin.config import Config
 from mypy_django_plugin.transformers import fields, init_create
+from mypy_django_plugin.transformers.forms import make_meta_nested_class_inherit_from_any
 from mypy_django_plugin.transformers.migrations import determine_model_cls_from_string_for_migrations, \
     get_string_value_from_expr
 from mypy_django_plugin.transformers.models import process_model_class
@@ -33,6 +34,14 @@ def transform_manager_class(ctx: ClassDefContext) -> None:
         sym.node.metadata['django']['manager_bases'][ctx.cls.fullname] = 1
 
 
+def transform_modelform_class(ctx: ClassDefContext) -> None:
+    sym = ctx.api.lookup_fully_qualified_or_none(helpers.MODELFORM_CLASS_FULLNAME)
+    if sym is not None and isinstance(sym.node, TypeInfo):
+        sym.node.metadata['django']['modelform_bases'][ctx.cls.fullname] = 1
+
+    make_meta_nested_class_inherit_from_any(ctx)
+
+
 def determine_proper_manager_type(ctx: FunctionContext) -> Type:
     api = cast(TypeChecker, ctx.api)
     ret = ctx.default_return_type
@@ -176,22 +185,27 @@ class DjangoPlugin(Plugin):
     def _get_current_model_bases(self) -> Dict[str, int]:
         model_sym = self.lookup_fully_qualified(helpers.MODEL_CLASS_FULLNAME)
         if model_sym is not None and isinstance(model_sym.node, TypeInfo):
-            if 'django' not in model_sym.node.metadata:
-                model_sym.node.metadata['django'] = {
-                    'model_bases': {helpers.MODEL_CLASS_FULLNAME: 1}
-                }
-            return model_sym.node.metadata['django']['model_bases']
+            return (model_sym.node.metadata
+                    .setdefault('django', {})
+                    .setdefault('model_bases', {helpers.MODEL_CLASS_FULLNAME: 1}))
         else:
             return {}
 
     def _get_current_manager_bases(self) -> Dict[str, int]:
-        manager_sym = self.lookup_fully_qualified(helpers.MANAGER_CLASS_FULLNAME)
-        if manager_sym is not None and isinstance(manager_sym.node, TypeInfo):
-            if 'django' not in manager_sym.node.metadata:
-                manager_sym.node.metadata['django'] = {
-                    'manager_bases': {helpers.MANAGER_CLASS_FULLNAME: 1}
-                }
-            return manager_sym.node.metadata['django']['manager_bases']
+        model_sym = self.lookup_fully_qualified(helpers.MANAGER_CLASS_FULLNAME)
+        if model_sym is not None and isinstance(model_sym.node, TypeInfo):
+            return (model_sym.node.metadata
+                    .setdefault('django', {})
+                    .setdefault('manager_bases', {helpers.MANAGER_CLASS_FULLNAME: 1}))
+        else:
+            return {}
+
+    def _get_current_modelform_bases(self) -> Dict[str, int]:
+        model_sym = self.lookup_fully_qualified(helpers.MODELFORM_CLASS_FULLNAME)
+        if model_sym is not None and isinstance(model_sym.node, TypeInfo):
+            return (model_sym.node.metadata
+                    .setdefault('django', {})
+                    .setdefault('modelform_bases', {helpers.MODELFORM_CLASS_FULLNAME: 1}))
         else:
             return {}
 
@@ -230,6 +244,12 @@ class DjangoPlugin(Plugin):
         if fullname in self._get_current_model_bases():
             return transform_model_class
 
+        if fullname in self._get_current_manager_bases():
+            return transform_manager_class
+
+        if fullname in self._get_current_modelform_bases():
+            return transform_modelform_class
+
         if fullname == helpers.DUMMY_SETTINGS_BASE_CLASS:
             settings_modules = ['django.conf.global_settings']
             if self.django_settings_module:
@@ -237,9 +257,6 @@ class DjangoPlugin(Plugin):
             return AddSettingValuesToDjangoConfObject(settings_modules,
                                                       self.config.ignore_missing_settings)
 
-        if fullname in self._get_current_manager_bases():
-            return transform_manager_class
-
         return None
 
     def get_attribute_hook(self, fullname: str

mypy_django_plugin/transformers/forms.py

@@ -0,0 +1,9 @@
+from mypy.plugin import ClassDefContext
+from mypy_django_plugin import helpers
+
+
+def make_meta_nested_class_inherit_from_any(ctx: ClassDefContext) -> None:
+    meta_node = helpers.get_nested_meta_node_for_current_class(ctx.cls.info)
+    if meta_node is None:
+        return None
+    meta_node.fallback_to_any = True

mypy_django_plugin/transformers/models.py

@@ -21,14 +21,8 @@ class ModelClassInitializer(metaclass=ABCMeta):
     def from_ctx(cls, ctx: ClassDefContext):
         return cls(api=cast(SemanticAnalyzerPass2, ctx.api), model_classdef=ctx.cls)
 
-    def get_nested_meta_node(self) -> Optional[TypeInfo]:
-        metaclass_sym = self.model_classdef.info.names.get('Meta')
-        if metaclass_sym is not None and isinstance(metaclass_sym.node, TypeInfo):
-            return metaclass_sym.node
-        return None
-
     def get_meta_attribute(self, name: str) -> Optional[Expression]:
-        meta_node = self.get_nested_meta_node()
+        meta_node = helpers.get_nested_meta_node_for_current_class(self.model_classdef.info)
         if meta_node is None:
             return None
 
@@ -80,7 +74,7 @@ class SetIdAttrsForRelatedFields(ModelClassInitializer):
 
 class InjectAnyAsBaseForNestedMeta(ModelClassInitializer):
     def run(self) -> None:
-        meta_node = self.get_nested_meta_node()
+        meta_node = helpers.get_nested_meta_node_for_current_class(self.model_classdef.info)
         if meta_node is None:
             return None
         meta_node.fallback_to_any = True

test-data/typecheck/forms.test

@@ -0,0 +1,19 @@
+[CASE no_incompatible_meta_nested_class_false_positive]
+from django.db import models
+from django import forms
+
+class Article(models.Model):
+    pass
+class Category(models.Model):
+    pass
+class ArticleForm(forms.ModelForm):
+    class Meta:
+        model = Article
+        fields = '__all__'
+class CategoryForm(forms.ModelForm):
+    class Meta:
+        model = Category
+        fields = '__all__'
+class CompositeForm(ArticleForm, CategoryForm):
+    pass
+[out]