lookup manager type via mro (#21)

Co-authored-by: Anthony Sottile <asottile@umich.edu>

Author: asottile-sentry

mypy_django_plugin/transformers/models.py

@@ -329,7 +329,7 @@ def run_with_model_cls(self, model_cls: Type[Model]) -> None:
 
         incomplete_manager_defs = set()
         for manager_name, manager in model_cls._meta.managers_map.items():
-            manager_node = self.model_classdef.info.names.get(manager_name, None)
+            manager_node = self.model_classdef.info.get(manager_name)
             manager_fullname = helpers.get_class_fullname(manager.__class__)
             manager_info = self.lookup_manager(manager_fullname, manager)
 
@@ -346,7 +346,8 @@ def run_with_model_cls(self, model_cls: Type[Model]) -> None:
                 incomplete_manager_defs.add(manager_name)
                 continue
 
-            manager_type = Instance(manager_info, [Instance(self.model_classdef.info, [])])
+            assert self.model_classdef.info.self_type is not None
+            manager_type = Instance(manager_info, [self.model_classdef.info.self_type])
             self.add_new_node_to_model_class(manager_name, manager_type, is_classvar=True)
 
         if incomplete_manager_defs:
@@ -362,9 +363,10 @@ def run_with_model_cls(self, model_cls: Type[Model]) -> None:
                 # setting _some_ type
                 fallback_manager_info = self.get_or_create_manager_with_any_fallback()
                 if fallback_manager_info is not None:
+                    assert self.model_classdef.info.self_type is not None
                     self.add_new_node_to_model_class(
                         manager_name,
-                        Instance(fallback_manager_info, [Instance(self.model_classdef.info, [])]),
+                        Instance(fallback_manager_info, [self.model_classdef.info.self_type]),
                         is_classvar=True,
                     )
 

tests/typecheck/managers/test_managers.yml

@@ -543,7 +543,6 @@
         myapp/models:23: error: Could not resolve manager type for "myapp.models.TwoUnresolvable.objects"  [django-manager-missing]
         myapp/models:24: error: Could not resolve manager type for "myapp.models.TwoUnresolvable.second_objects"  [django-manager-missing]
         myapp/models:27: error: Could not resolve manager type for "myapp.models.AbstractUnresolvable.objects"  [django-manager-missing]
-        myapp/models:32: error: Could not resolve manager type for "myapp.models.InvisibleUnresolvable.objects"  [django-manager-missing]
         myapp/models:36: note: Revealed type is "django.db.models.manager.Manager[myapp.models.User]"
         myapp/models:37: note: Revealed type is "django.db.models.manager.Manager[myapp.models.User]"
         myapp/models:39: note: Revealed type is "myapp.models.UnknownManager[myapp.models.Booking]"

tests/typecheck/models/test_inheritance.yml

@@ -109,3 +109,44 @@
                         abstract = True
                 class User(Mixin1, Mixin2):
                     name = models.TextField()
+
+-   case: test_manager_typevar_through_bounds
+    main: |
+        from myapp.models import ResultProcessorConcrete
+        reveal_type(ResultProcessorConcrete().f())  # N: Revealed type is "myapp.models.Concrete"
+    installed_apps:
+        -   myapp
+    files:
+        -   path: myapp/__init__.py
+        -   path: myapp/models.py
+            content: |
+                from __future__ import annotations
+
+                from django.db.models import Model
+                from django.db.models.manager import Manager
+                from typing import TypeVar, Generic, ClassVar
+                from typing_extensions import Self
+
+                M = TypeVar("M", bound=Model, covariant=True)
+
+                class BaseManager(Manager[M]): ...
+
+                class Base(Model):
+                    custom_objects: ClassVar[BaseManager[Self]] = BaseManager()
+
+                class Bound(Base): pass
+
+                T = TypeVar("T", bound=Bound)
+
+                class ResultProcessorBase(Generic[T]):
+                    @property
+                    def model_cls(self) -> type[T]:
+                        raise NotImplementedError
+
+                    def f(self) -> T:
+                        return self.model_cls.custom_objects.get()
+
+                class Concrete(Bound): pass
+
+                class ResultProcessorConcrete(ResultProcessorBase[Concrete]):
+                    pass