Fixed #28838 -- Fixed Model.save() crash if the base manager annotates with a related field.

2 files changed, 29 insertions, 1 deletions

diff --git a/tests/custom_managers/models.py b/tests/custom_managers/models.py
index f90425db3c..ca2e14b047 100644
--- a/tests/custom_managers/models.py
+++ b/tests/custom_managers/models.py
@@ -25,6 +25,13 @@ class PublishedBookManager(models.Manager):
         return super().get_queryset().filter(is_published=True)
 
 
+class AnnotatedBookManager(models.Manager):
+    def get_queryset(self):
+        return super().get_queryset().annotate(
+            favorite_avg=models.Avg('favorite_books__favorite_thing_id')
+        )
+
+
 class CustomQuerySet(models.QuerySet):
     def filter(self, *args, **kwargs):
         queryset = super().filter(fun=True)
@@ -131,7 +138,6 @@ class Book(models.Model):
     title = models.CharField(max_length=50)
     author = models.CharField(max_length=30)
     is_published = models.BooleanField(default=False)
-    published_objects = PublishedBookManager()
     authors = models.ManyToManyField(Person, related_name='books')
     fun_authors = models.ManyToManyField(FunPerson, related_name='books')
     favorite_things = GenericRelation(
@@ -145,6 +151,12 @@ class Book(models.Model):
         object_id_field='favorite_thing_id',
     )
 
+    published_objects = PublishedBookManager()
+    annotated_objects = AnnotatedBookManager()
+
+    class Meta:
+        base_manager_name = 'annotated_objects'
+
     def __str__(self):
         return self.title
 
diff --git a/tests/custom_managers/tests.py b/tests/custom_managers/tests.py
index a545382d8f..8e5ab1418f 100644
--- a/tests/custom_managers/tests.py
+++ b/tests/custom_managers/tests.py
@@ -617,6 +617,22 @@ class CustomManagersRegressTestCase(TestCase):
         book.refresh_from_db()
         self.assertEqual(book.title, 'Hi')
 
+    def test_save_clears_annotations_from_base_manager(self):
+        """Model.save() clears annotations from the base manager."""
+        self.assertEqual(Book._meta.base_manager.name, 'annotated_objects')
+        book = Book.annotated_objects.create(title='Hunting')
+        Person.objects.create(
+            first_name='Bugs', last_name='Bunny', fun=True,
+            favorite_book=book, favorite_thing_id=1,
+        )
+        book = Book.annotated_objects.first()
+        self.assertEqual(book.favorite_avg, 1)  # Annotation from the manager.
+        book.title = 'New Hunting'
+        # save() fails if annotations that involve related fields aren't
+        # cleared before the update query.
+        book.save()
+        self.assertEqual(Book.annotated_objects.first().title, 'New Hunting')
+
     def test_delete_related_on_filtered_manager(self):
         """Deleting related objects should also not be distracted by a
         restricted manager on the related object. This is a regression