managers: honor OneToOneField.parent_link=False (#363)

CHANGES.rst

@@ -3,6 +3,7 @@ CHANGES
 
 master (unreleased)
 -------------------
+- Honor `OneToOneField.parent_link=False`.
 - Fix handling of deferred attributes on Django 1.10+, fixes GH-278
 - Fix `FieldTracker.has_changed()` and `FieldTracker.previous()` to return
   correct responses for deferred fields.

model_utils/managers.py

@@ -158,6 +158,7 @@ class InheritanceQuerySetMixin(object):
             if isinstance(rel.field, OneToOneField)
             and issubclass(rel.field.model, model)
             and model is not rel.field.model
+            and rel.parent_link
         ]
 
         subclasses = []

tests/models.py

@@ -73,6 +73,16 @@ class InheritanceManagerTestChild3(InheritanceManagerTestParent):
         InheritanceManagerTestParent, related_name='manual_onetoone',
         parent_link=True, on_delete=models.CASCADE)
 
+class InheritanceManagerTestChild4(InheritanceManagerTestParent):
+    other_onetoone = models.OneToOneField(
+        InheritanceManagerTestParent, related_name='non_inheritance_relation',
+        parent_link=False, on_delete=models.CASCADE)
+    # The following is needed because of that Django bug:
+    # https://code.djangoproject.com/ticket/29998
+    parent_ptr = models.OneToOneField(
+        InheritanceManagerTestParent, related_name='child4_onetoone',
+        parent_link=True, on_delete=models.CASCADE)
+
 
 class TimeStamp(TimeStampedModel):
     pass

tests/test_managers/test_inheritance_manager.py

@@ -10,7 +10,8 @@ from tests.models import (
     InheritanceManagerTestRelated, InheritanceManagerTestGrandChild1,
     InheritanceManagerTestGrandChild1_2, InheritanceManagerTestParent,
     InheritanceManagerTestChild1,
-    InheritanceManagerTestChild2, TimeFrame, InheritanceManagerTestChild3
+    InheritanceManagerTestChild2, TimeFrame, InheritanceManagerTestChild3,
+    InheritanceManagerTestChild4,
 )
 
 
@@ -141,6 +142,7 @@ class InheritanceManagerTests(TestCase):
             'inheritancemanagertestchild1',
             'inheritancemanagertestchild2',
             'manual_onetoone',  # this was set via parent_link & related_name
+            'child4_onetoone',
         ]
         self.assertEqual(set(results.subclasses),
                          set(expected_related_names))
@@ -258,7 +260,7 @@ class InheritanceManagerUsingModelsTests(TestCase):
         objs = InheritanceManagerTestParent.objects.select_subclasses().order_by('pk')
         objsmodels = InheritanceManagerTestParent.objects.select_subclasses(
             InheritanceManagerTestChild1, InheritanceManagerTestChild2,
-            InheritanceManagerTestChild3,
+            InheritanceManagerTestChild3, InheritanceManagerTestChild4,
             InheritanceManagerTestGrandChild1,
             InheritanceManagerTestGrandChild1_2).order_by('pk')
         self.assertEqual(set(objs.subclasses), set(objsmodels.subclasses))
@@ -280,6 +282,7 @@ class InheritanceManagerUsingModelsTests(TestCase):
         models = (InheritanceManagerTestChild1,
                   InheritanceManagerTestChild2,
                   InheritanceManagerTestChild3,
+                  InheritanceManagerTestChild4,
                   InheritanceManagerTestGrandChild1,
                   InheritanceManagerTestGrandChild1_2)