fixup! Don't remove objects attribute from Model in plugin

Author: flaeppe

django-stubs/contrib/sites/managers.pyi

@@ -1,8 +1,9 @@
 from typing import TypeVar
 
+from django.contrib.sites.models import Site
 from django.db import models
 
-_T = TypeVar("_T", bound=models.Model)
+_T = TypeVar("_T", bound=Site)
 
 class CurrentSiteManager(models.Manager[_T]):
     def __init__(self, field_name: str | None = ...) -> None: ...

mypy_django_plugin/transformers/models.py

@@ -352,23 +352,23 @@ def cast_var_to_classvar(symbol: Optional[SymbolTableNode]) -> None:
 
             assert self.model_classdef.info.self_type is not None
             manager_type = Instance(manager_info, [self.model_classdef.info.self_type])
+            # It seems that the type checker fetches a Var from expressions, but looks
+            # through the symbol table for the type(at some later stage?). Currently we
+            # don't overwrite the reference mypy holds from an expression to a Var
+            # instance when adding a new node, we only overwrite the reference to the
+            # Var in the symbol table. That means there's a lingering Var instance
+            # attached to expressions and if we don't flip that to a ClassVar, the
+            # checker will emit an error for overriding a class variable with an
+            # instance variable. As mypy seems to check that via the expression and not
+            # the symbol table. Optimally we want to just set a type on the existing Var
+            # like:
+            # manager_node.node.type = manager_type
+            # but for some reason that doesn't work. It only works replacing the
+            # existing Var with a new one in the symbol table.
+            cast_var_to_classvar(manager_node)
             if manager_fullname == manager_info.fullname and manager_node and isinstance(manager_node.node, Var):
                 manager_node.node.type = manager_type
             else:
-                # It seems that the type checker fetches a Var from expressions, but
-                # looks through the symbol table for the type(at some later stage?).
-                # Currently we don't overwrite the reference mypy holds from an
-                # expression to a Var instance when adding a new node, we only overwrite
-                # the reference to the Var in the symbol table. That means there's a
-                # lingering Var instance attached to expressions and if we don't flip
-                # that to a ClassVar, the checker will emit an error for overriding a
-                # class variable with an instance variable. As mypy seems to check that
-                # via the expression and not the symbol table. Optimally we want to just
-                # set a type on the existing Var like
-                # manager_node.node.type = manager_type
-                # but for some reason that doesn't work. It only works replacing the
-                # existing Var with a new one in the symbol table.
-                cast_var_to_classvar(manager_node)
                 self.add_new_node_to_model_class(manager_name, manager_type, is_classvar=True)
 
         if incomplete_manager_defs:

tests/typecheck/managers/test_managers.yml

@@ -169,29 +169,28 @@
     main: |
         from myapp.models import AbstractPerson, Book
         reveal_type(AbstractPerson.abstract_persons)  # N: Revealed type is "django.db.models.manager.Manager[myapp.models.AbstractPerson]"
-        reveal_type(Book.published_objects)  # N: Revealed type is "myapp.models.PublishedBookManager"
+        reveal_type(Book.published_objects)  # N: Revealed type is "myapp.models.PublishedBookManager[myapp.models.Book]"
         Book.published_objects.create(title='hello')
-        reveal_type(Book.annotated_objects)  # N: Revealed type is "myapp.models.AnnotatedBookManager"
+        reveal_type(Book.annotated_objects)  # N: Revealed type is "myapp.models.AnnotatedBookManager[myapp.models.Book]"
         Book.annotated_objects.create(title='hello')
     installed_apps:
         - myapp
     files:
         -   path: myapp/__init__.py
         -   path: myapp/models.py
             content: |
-                from typing import ClassVar
                 from django.db import models
 
                 class AbstractPerson(models.Model):
-                    abstract_persons: ClassVar[models.Manager["AbstractPerson"]] = models.Manager['AbstractPerson']()
+                    abstract_persons = models.Manager['AbstractPerson']()
                 class PublishedBookManager(models.Manager['Book']):
                     pass
                 class AnnotatedBookManager(models.Manager['Book']):
                     pass
                 class Book(models.Model):
                     title = models.CharField(max_length=50)
-                    published_objects: ClassVar[PublishedBookManager] = PublishedBookManager()
-                    annotated_objects: ClassVar[AnnotatedBookManager] = AnnotatedBookManager()
+                    published_objects = PublishedBookManager()
+                    annotated_objects = AnnotatedBookManager()
 
 -   case: managers_inherited_from_abstract_classes_multiple_inheritance
     main: |
@@ -201,32 +200,31 @@
         reveal_type(AbstractBase1.manager1)
         reveal_type(AbstractBase2.restricted)
     out: |
-        main:2: note: Revealed type is "myapp.models.CustomManager1"
-        main:3: note: Revealed type is "myapp.models.CustomManager2"
-        main:4: note: Revealed type is "myapp.models.CustomManager1"
-        main:5: note: Revealed type is "myapp.models.CustomManager2"
+        main:2: note: Revealed type is "myapp.models.CustomManager1[myapp.models.Child]"
+        main:3: note: Revealed type is "myapp.models.CustomManager2[myapp.models.Child]"
+        main:4: note: Revealed type is "myapp.models.CustomManager1[myapp.models.AbstractBase1]"
+        main:5: note: Revealed type is "myapp.models.CustomManager2[myapp.models.AbstractBase2]"
     installed_apps:
         - myapp
     files:
         -   path: myapp/__init__.py
         -   path: myapp/models.py
             content: |
-                from typing import ClassVar
                 from django.db import models
                 class CustomManager1(models.Manager['AbstractBase1']):
                     pass
                 class AbstractBase1(models.Model):
                     class Meta:
                         abstract = True
                     name = models.CharField(max_length=50)
-                    manager1: ClassVar[CustomManager1] = CustomManager1()
+                    manager1 = CustomManager1()
                 class CustomManager2(models.Manager['AbstractBase2']):
                     pass
                 class AbstractBase2(models.Model):
                     class Meta:
                         abstract = True
                     value = models.CharField(max_length=50)
-                    restricted: ClassVar[CustomManager2] = CustomManager2()
+                    restricted = CustomManager2()
 
                 class Child(AbstractBase1, AbstractBase2):
                     pass
@@ -453,15 +451,13 @@
         -   path: myapp/__init__.py
         -   path: myapp/models.py
             content: |
-                from typing import ClassVar
-                from typing_extensions import Self
                 from django.db import models
                 from django.contrib.sites.models import Site
                 from django.contrib.sites.managers import CurrentSiteManager
 
                 class MyModel(models.Model):
                     site = models.ForeignKey(Site, on_delete=models.CASCADE)
-                    on_site: ClassVar[CurrentSiteManager[Self]] = CurrentSiteManager()
+                    on_site = CurrentSiteManager()
 
 -   case: test_emits_error_for_unresolved_managers
     main: |

tests/typecheck/models/test_contrib_models.yml

@@ -38,7 +38,7 @@
 -   case: can_override_abstract_user_manager
     main: |
         from myapp.models import MyBaseUser, MyUser
-        reveal_type(MyBaseUser.objects)  # N: Revealed type is "myapp.models.MyBaseUserManager"
+        reveal_type(MyBaseUser.objects)  # N: Revealed type is "myapp.models.MyBaseUserManager[myapp.models.MyBaseUser]"
         reveal_type(MyBaseUser.objects.all())  # N: Revealed type is "django.db.models.query.QuerySet[myapp.models.MyBaseUser, myapp.models.MyBaseUser]"
         reveal_type(MyUser.objects)  # N: Revealed type is "myapp.models.MyUserManager"
         reveal_type(MyUser.objects.all())  # N: Revealed type is "django.db.models.query.QuerySet[myapp.models.MyUser, myapp.models.MyUser]"
@@ -56,7 +56,7 @@
                   ...
 
               class MyBaseUser(AbstractBaseUser):
-                  objects: ClassVar[MyBaseUserManager] = MyBaseUserManager()
+                  objects = MyBaseUserManager()
 
               class MyUserManager(UserManager["MyUser"]):
                   ...