Fixed #20883 -- Made model inheritance find parent links in abstract parents

django/db/models/base.py

@@ -184,10 +184,21 @@ class ModelBase(type):
         else:
             new_class._meta.concrete_model = new_class
 
-        # Do the appropriate setup for any model parents.
+        # Collect the parent links for multi-table inheritance.
-        o2o_map = dict([(f.rel.to, f) for f in new_class._meta.local_fields
+        parent_links = {}
-                if isinstance(f, OneToOneField)])
+        for base in reversed([new_class] + parents):
+            # Conceptually equivalent to `if base is Model`.
+            if not hasattr(base, '_meta'):
+                continue
+            # Skip concrete parent classes.
+            if base != new_class and not base._meta.abstract:
+                continue
+            # Locate OneToOneField instances.
+            for field in base._meta.local_fields:
+                if isinstance(field, OneToOneField):
+                    parent_links[field.rel.to] = field
 
+        # Do the appropriate setup for any model parents.
         for base in parents:
             original_base = base
             if not hasattr(base, '_meta'):
@@ -208,8 +219,8 @@ class ModelBase(type):
             if not base._meta.abstract:
                 # Concrete classes...
                 base = base._meta.concrete_model
-                if base in o2o_map:
+                if base in parent_links:
-                    field = o2o_map[base]
+                    field = parent_links[base]
                 elif not is_proxy:
                     attr_name = '%s_ptr' % base._meta.model_name
                     field = OneToOneField(base, name=attr_name,

docs/releases/1.7.txt

@@ -142,6 +142,9 @@ Minor features
   the file system permissions of directories created during file upload, like
   :setting:`FILE_UPLOAD_PERMISSIONS` does for the files themselves.
 
+* Explicit :class:`~django.db.models.OneToOneField` for
+  :ref:`multi-table-inheritance` are now discovered in abstract classes.
+
 Backwards incompatible changes in 1.7
 =====================================
 

tests/model_inheritance_regress/models.py

@@ -50,6 +50,19 @@ class ParkingLot3(Place):
     primary_key = models.AutoField(primary_key=True)
     parent = models.OneToOneField(Place, parent_link=True)
 
+class ParkingLot4(models.Model):
+    # Test parent_link connector can be discovered in abstract classes.
+    parent = models.OneToOneField(Place, parent_link=True)
+
+    class Meta:
+        abstract = True
+
+class ParkingLot4A(ParkingLot4, Place):
+    pass
+
+class ParkingLot4B(Place, ParkingLot4):
+    pass
+
 class Supplier(models.Model):
     restaurant = models.ForeignKey(Restaurant)
 

tests/model_inheritance_regress/tests.py

@@ -14,7 +14,8 @@ from .models import (Place, Restaurant, ItalianRestaurant, ParkingLot,
     ParkingLot2, ParkingLot3, Supplier, Wholesaler, Child, SelfRefParent,
     SelfRefChild, ArticleWithAuthor, M2MChild, QualityControl, DerivedM,
     Person, BirthdayParty, BachelorParty, MessyBachelorParty,
-    InternalCertificationAudit, BusStation, TrainStation, User, Profile)
+    InternalCertificationAudit, BusStation, TrainStation, User, Profile,
+    ParkingLot4A, ParkingLot4B)
 
 
 class ModelInheritanceTest(TestCase):
@@ -311,6 +312,19 @@ class ModelInheritanceTest(TestCase):
             ParkingLot3._meta.get_ancestor_link(Place).name,
             "parent")
 
+    def test_use_explicit_o2o_to_parent_from_abstract_model(self):
+        self.assertEqual(ParkingLot4A._meta.pk.name, "parent")
+        ParkingLot4A.objects.create(
+            name="Parking4A",
+            address='21 Jump Street',
+        )
+
+        self.assertEqual(ParkingLot4B._meta.pk.name, "parent")
+        ParkingLot4A.objects.create(
+            name="Parking4B",
+            address='21 Jump Street',
+        )
+
     def test_all_fields_from_abstract_base_class(self):
         """
         Regression tests for #7588