Fixed bugs in superclass/subclass field link processingso that this can cope with proxy models, as well as parent_link and related_name links to parents.

Added a test case for testing parent_link and related_name links to parent.

All tests pass should pass now (at least they do for me on django 1.5 and python 2.7)

polymorphic/polymorphic_model.py

@@ -22,7 +22,7 @@ from django.utils import six
 from .base import PolymorphicModelBase
 from .manager import PolymorphicManager
 from .query_translate import translate_polymorphic_Q_object
-
+import pdb
 
 ###################################################################################
 ### PolymorphicModel
@@ -185,22 +185,25 @@ class PolymorphicModel(six.with_metaclass(PolymorphicModelBase, models.Model)):
 
         def add_all_super_models(model, result):    
             for super_cls, field_to_super in model._meta.parents.iteritems():
-                field_name = field_to_super.name #the field on model can have a different name to super_cls._meta.module_name, if the field is created manually using 'parent_link'
-                add_model_if_regular(super_cls, field_name, result)
-                add_all_super_models(super_cls, result)
+                if field_to_super is not None:  #if not a link to a proxy model
+                    field_name = field_to_super.name #the field on model can have a different name to super_cls._meta.module_name, if the field is created manually using 'parent_link'
+                    add_model_if_regular(super_cls, field_name, result)
+                    add_all_super_models(super_cls, result)
 
         def add_all_sub_models(super_cls, result):            
             for sub_cls in super_cls.__subclasses__(): #go through all subclasses of model  
-                field_to_super = sub_cls._meta.parents[super_cls] #get the field that links sub_cls to super_cls           
-                super_to_sub_related_field = field_to_super.rel
-                if super_to_sub_related_field.related_name is None:
-                    #if related name is None the related field is the name of the subclass
-                    to_subclass_fieldname = sub_cls.__name__.lower()
-                else:
-                    #otherwise use the given related name
-                    to_subclass_fieldname = super_to_sub_related_field.related_name
+                if super_cls in sub_cls._meta.parents: #super_cls may not be in sub_cls._meta.parents if super_cls is a proxy model
+                    field_to_super = sub_cls._meta.parents[super_cls] #get the field that links sub_cls to super_cls    
+                    if field_to_super is not None:    # if filed_to_super is not a link to a proxy model
+                        super_to_sub_related_field = field_to_super.rel
+                        if super_to_sub_related_field.related_name is None:
+                            #if related name is None the related field is the name of the subclass
+                            to_subclass_fieldname = sub_cls.__name__.lower()
+                        else:
+                            #otherwise use the given related name
+                            to_subclass_fieldname = super_to_sub_related_field.related_name
                             
-                add_model_if_regular(sub_cls, to_subclass_fieldname, result)
+                        add_model_if_regular(sub_cls, to_subclass_fieldname, result)
 
         result = {}
         add_all_super_models(self.__class__, result)

polymorphic/tests.py

@@ -245,6 +245,10 @@ class ProxyModelB(ProxyModelBase):
 class RelatedNameClash(ShowFieldType, PolymorphicModel):
     ctype = models.ForeignKey(ContentType, null=True, editable=False)
 
+#class with a parent_link to superclass, and a related_name back to subclass
+class TestParentLinkAndRelatedName(ModelShow1_plain):
+    superclass = models.OneToOneField(ModelShow1_plain, parent_link=True, related_name = 'related_name_subclass')
+
 
 class PolymorphicTests(TestCase):
     """
@@ -767,6 +771,24 @@ class PolymorphicTests(TestCase):
         o = InitTestModelSubclass.objects.create()
         self.assertEqual(o.bar, 'XYZ')
 
+    def test_parent_link_and_related_name(self):
+        t = TestParentLinkAndRelatedName(field1 = "TestParentLinkAndRelatedName")
+        t.save()
+        p = ModelShow1_plain.objects.get(field1 = "TestParentLinkAndRelatedName")
+        
+        #check that p is equal to the 
+        self.assertIsInstance(p, TestParentLinkAndRelatedName)
+        self.assertEqual(p, t)
+        
+        #check that the accessors to parent and sublass work correctly and return the right object
+        p = ModelShow1_plain.objects.non_polymorphic().get(field1 = "TestParentLinkAndRelatedName")
+        self.assertNotEqual(p, t) #p should be Plain1 and t TestParentLinkAndRelatedName, so not equal
+        self.assertEqual(p, t.superclass)
+        self.assertEqual(p.related_name_subclass, t)
+        
+        #test that we can delete t 
+        t.delete()
+        
 
 class RegressionTests(TestCase):