Use runtime information to determine whether class is a models.Model subclass (#182)

mypy_django_plugin/django/context.py

@@ -6,6 +6,7 @@ from typing import (
 )
 
 from django.core.exceptions import FieldError
+from django.db import models
 from django.db.models.base import Model
 from django.db.models.fields import AutoField, CharField, Field
 from django.db.models.fields.related import ForeignKey, RelatedField
@@ -285,3 +286,15 @@ class DjangoContext:
                 expected_types[field_name] = gfk_set_type
 
         return expected_types
+
+    @cached_property
+    def model_base_classes(self) -> Set[str]:
+        model_classes = self.apps_registry.get_models()
+
+        all_model_bases = set()
+        for model_cls in model_classes:
+            for base_cls in model_cls.mro():
+                if issubclass(base_cls, models.Model):
+                    all_model_bases.add(helpers.get_class_fullname(base_cls))
+
+        return all_model_bases

mypy_django_plugin/lib/helpers.py

@@ -255,8 +255,6 @@ def get_typechecker_api(ctx: Union[AttributeContext, MethodContext, FunctionCont
     return cast(TypeChecker, ctx.api)
 
 
-def get_all_model_mixins(api: TypeChecker) -> Set[str]:
-    basemodel_info = lookup_fully_qualified_typeinfo(api, fullnames.MODEL_CLASS_FULLNAME)
-    if basemodel_info is None:
-        return set()
-    return set(get_django_metadata(basemodel_info).get('model_mixins', dict).keys())
+def is_model_subclass_info(info: TypeInfo, django_context: 'DjangoContext') -> bool:
+    return (info.fullname() in django_context.model_base_classes
+            or info.has_base(fullnames.MODEL_CLASS_FULLNAME))

mypy_django_plugin/main.py

@@ -174,7 +174,7 @@ class NewSemanalDjangoPlugin(Plugin):
             if info.has_base(fullnames.FIELD_FULLNAME):
                 return partial(fields.transform_into_proper_return_type, django_context=self.django_context)
 
-            if info.has_base(fullnames.MODEL_CLASS_FULLNAME):
+            if helpers.is_model_subclass_info(info, self.django_context):
                 return partial(init_create.redefine_and_typecheck_model_init, django_context=self.django_context)
         return None
 
@@ -213,7 +213,8 @@ class NewSemanalDjangoPlugin(Plugin):
 
     def get_base_class_hook(self, fullname: str
                             ) -> Optional[Callable[[ClassDefContext], None]]:
-        if fullname in self._get_current_model_bases():
+        if (fullname in self.django_context.model_base_classes
+                or fullname in self._get_current_model_bases()):
             return partial(transform_model_class, django_context=self.django_context)
 
         if fullname in self._get_current_manager_bases():

mypy_django_plugin/transformers/fields.py

@@ -15,7 +15,7 @@ from mypy_django_plugin.lib import fullnames, helpers
 def _get_current_field_from_assignment(ctx: FunctionContext, django_context: DjangoContext) -> Optional[Field]:
     outer_model_info = helpers.get_typechecker_api(ctx).scope.active_class()
     if (outer_model_info is None
-            or not outer_model_info.has_base(fullnames.MODEL_CLASS_FULLNAME)):
+            or not helpers.is_model_subclass_info(outer_model_info, django_context)):
         return None
 
     field_name = None
@@ -117,10 +117,9 @@ def transform_into_proper_return_type(ctx: FunctionContext, django_context: Djan
 
     outer_model_info = helpers.get_typechecker_api(ctx).scope.active_class()
     if (outer_model_info is None
-            or not outer_model_info.has_base(fullnames.MODEL_CLASS_FULLNAME)
-            and outer_model_info.fullname() not in helpers.get_all_model_mixins(helpers.get_typechecker_api(ctx))):
-        # not inside models.Model class
+            or not helpers.is_model_subclass_info(outer_model_info, django_context)):
         return ctx.default_return_type
+
     assert isinstance(outer_model_info, TypeInfo)
 
     if helpers.has_any_of_bases(default_return_type.type, fullnames.RELATED_FIELDS_CLASSES):

mypy_django_plugin/transformers/models.py

@@ -218,18 +218,6 @@ class AddMetaOptionsAttribute(ModelClassInitializer):
                                              ]))
 
 
-class RecordAllModelMixins(ModelClassInitializer):
-    def run(self) -> None:
-        basemodel_info = self.lookup_typeinfo_or_incomplete_defn_error(fullnames.MODEL_CLASS_FULLNAME)
-        basemodel_metadata = helpers.get_django_metadata(basemodel_info)
-        if 'model_mixins' not in basemodel_metadata:
-            basemodel_metadata['model_mixins'] = {}
-
-        for base_info in self.model_classdef.info.mro[1:]:
-            if base_info.fullname() != 'builtins.object':
-                basemodel_metadata['model_mixins'][base_info.fullname()] = 1
-
-
 def process_model_class(ctx: ClassDefContext,
                         django_context: DjangoContext) -> None:
     initializers = [
@@ -241,7 +229,6 @@ def process_model_class(ctx: ClassDefContext,
         AddRelatedManagers,
         AddExtraFieldMethods,
         AddMetaOptionsAttribute,
-        RecordAllModelMixins,
     ]
     for initializer_cls in initializers:
         try:

test-data/typecheck/fields/test_base.yml

@@ -144,7 +144,10 @@
         -   path: myapp/models.py
             content: |
                 from django.db import models
-                class AuthMixin:
+                class AuthMixin(models.Model):
+                    class Meta:
+                        abstract = True
                     username = models.CharField(max_length=100)
+
                 class MyModel(AuthMixin, models.Model):
                     pass