fix custom PKs

taggit/managers.py

@@ -102,7 +102,7 @@ class TaggableManager(object):
     def m2m_reverse_name(self):
         if self.use_gfk:
             return "id"
-        return self.through._meta.get_field('content_object').rel.to._meta.pk.column
+        return self.through._meta.pk.column
 
     def m2m_column_name(self):
         if self.use_gfk:

taggit/tests/tests.py

@@ -70,7 +70,8 @@ class TaggableManagerTestCase(BaseTaggingTest):
         
         apple.delete()
         self.assert_tags_equal(self.food_model.tags.all(), ["green"])
-        
+
+    def test_require_pk(self):
         f = self.food_model()
         with self.assert_raises(ValueError):
             f.tags.all()
@@ -178,6 +179,10 @@ class TaggableManagerCustomPKTestCase(TaggableManagerTestCase):
     housepet_model = CustomPKHousePet
     taggeditem_model = TaggedCustomPKPet
 
+    def test_require_pk(self):
+        # XXX with a charfield pk, pk is never None, so taggit has no
+        # way to tell if the instance is saved or not
+        pass
 
 class TaggableFormTestCase(BaseTaggingTest):
     form_class = FoodForm