[2.1.x] Fixed #29653 -- Fixed missing related_query_name reverse acce…

…ssor if GenericRelation is declared on an abstract base model.

Regression in 4ab027b.

Thanks Lauri Kainulainen for the report.

Backport of b5c7cb4 from master

django/db/models/base.py

@@ -279,7 +279,8 @@ def __new__(cls, name, bases, attrs, **kwargs):
                         )
                 else:
                     field = copy.deepcopy(field)
-                    field.mti_inherited = True
+                    if not base._meta.abstract:
+                        field.mti_inherited = True
                     new_class.add_to_class(field.name, field)
 
         # Copy indexes so that index names are unique when models extend an

docs/releases/2.1.1.txt

@@ -28,3 +28,7 @@ Bugfixes
 * Fixed a regression where the admin change form crashed if the user doesn't
   have the 'add' permission to a model that uses ``TabularInline``
   (:ticket:`29637`).
+
+* Fixed a regression where a ``related_query_name`` reverse accessor wasn't set
+  up when a ``GenericRelation`` is declared on an abstract base model
+  (:ticket:`29653`).

tests/generic_relations_regress/models.py

@@ -158,7 +158,7 @@ def save_form_data(self, *args, **kwargs):
 
 
 class HasLinks(models.Model):
-    links = SpecialGenericRelation(Link)
+    links = SpecialGenericRelation(Link, related_query_name='targets')
 
     class Meta:
         abstract = True

tests/generic_relations_regress/tests.py

@@ -273,3 +273,12 @@ def test_generic_reverse_relation_with_mti(self):
         link = Link.objects.create(content_object=place)
         result = Link.objects.filter(places=place)
         self.assertCountEqual(result, [link])
+
+    def test_generic_reverse_relation_with_abc(self):
+        """
+        The reverse generic relation accessor (targets) is created if the
+        GenericRelation comes from an abstract base model (HasLinks).
+        """
+        thing = HasLinkThing.objects.create()
+        link = Link.objects.create(content_object=thing)
+        self.assertCountEqual(link.targets.all(), [thing])