[1.2.X] Fixed #13987 -- Ensure that the primary key is set correctly for all models that have concrete-abstract-concrete inheritance, not just the first model. Thanks to Aramgutang for the report and patch.

Backport of r15498 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@15499 bcc190cf-cafb-0310-a4f2-bffc1f526a37

3 files changed, 45 insertions, 2 deletions

diff --git a/django/db/models/options.py b/django/db/models/options.py
index 3196a41ff2..5ff4b73161 100644
--- a/django/db/models/options.py
+++ b/django/db/models/options.py
@@ -118,6 +118,12 @@ class Options(object):
                 # Promote the first parent link in lieu of adding yet another
                 # field.
                 field = self.parents.value_for_index(0)
+                # Look for a local field with the same name as the
+                # first parent link. If a local field has already been
+                # created, use it instead of promoting the parent
+                already_created = [fld for fld in self.local_fields if fld.name == field.name]
+                if already_created:
+                    field = already_created[0]
                 field.primary_key = True
                 self.setup_pk(field)
             else:
diff --git a/tests/regressiontests/model_inheritance_regress/models.py b/tests/regressiontests/model_inheritance_regress/models.py
index 787f163349..bb5d77c51f 100644
--- a/tests/regressiontests/model_inheritance_regress/models.py
+++ b/tests/regressiontests/model_inheritance_regress/models.py
@@ -146,3 +146,20 @@ class BachelorParty(AbstractEvent):
 
 class MessyBachelorParty(BachelorParty):
     pass
+
+# Check concrete -> abstract -> concrete inheritance
+class SearchableLocation(models.Model):
+    keywords = models.CharField(max_length=256)
+
+class Station(SearchableLocation):
+    name = models.CharField(max_length=128)
+
+    class Meta:
+        abstract = True
+
+class BusStation(Station):
+    bus_routes = models.CommaSeparatedIntegerField(max_length=128)
+    inbound = models.BooleanField()
+
+class TrainStation(Station):
+    zone = models.IntegerField()
diff --git a/tests/regressiontests/model_inheritance_regress/tests.py b/tests/regressiontests/model_inheritance_regress/tests.py
index dac2cb5de5..1bb147e17c 100644
--- a/tests/regressiontests/model_inheritance_regress/tests.py
+++ b/tests/regressiontests/model_inheritance_regress/tests.py
@@ -11,7 +11,7 @@ from models import (Place, Restaurant, ItalianRestaurant, ParkingLot,
     ParkingLot2, ParkingLot3, Supplier, Wholesaler, Child, SelfRefParent,
     SelfRefChild, ArticleWithAuthor, M2MChild, QualityControl, DerivedM,
     Person, BirthdayParty, BachelorParty, MessyBachelorParty,
-    InternalCertificationAudit)
+    InternalCertificationAudit, BusStation, TrainStation)
 
 
 class ModelInheritanceTest(TestCase):
@@ -358,7 +358,7 @@ class ModelInheritanceTest(TestCase):
         parties = list(p4.bachelorparty_set.all())
         self.assertEqual(parties, [bachelor, messy_parent])
 
-    def test_11369(self):
+    def test_abstract_verbose_name_plural_inheritance(self):
         """
         verbose_name_plural correctly inherited from ABC if inheritance chain
         includes an abstract model.
@@ -386,3 +386,23 @@ class ModelInheritanceTest(TestCase):
             ],
             attrgetter("pk")
         )
+
+    def test_concrete_abstract_concrete_pk(self):
+        """
+        Primary key set correctly with concrete->abstract->concrete inheritance.
+        """
+        # Regression test for #13987: Primary key is incorrectly determined
+        # when more than one model has a concrete->abstract->concrete
+        # inheritance hierarchy.
+        self.assertEquals(
+            len([field for field in BusStation._meta.local_fields
+                       if field.primary_key]),
+            1
+        )
+        self.assertEquals(
+            len([field for field in TrainStation._meta.local_fields
+                       if field.primary_key]),
+            1
+        )
+        self.assertIs(BusStation._meta.pk.model, BusStation)
+        self.assertIs(TrainStation._meta.pk.model, TrainStation)