Fix calling create() on a related manager based on PassThroughManager.

CHANGES.rst

@@ -4,6 +4,9 @@ CHANGES
 tip (unreleased)
 ----------------
 
+- Fix calling ``create()`` on a ``RelatedManager`` that subclasses a dynamic
+  ``PassThroughManager``. Thanks SeiryuZ for the report. Fixes GH-24.
+
 - Add workaround for https://code.djangoproject.com/ticket/16855 in
   InheritanceQuerySet to avoid overriding prior calls to
   ``select_related()``. Thanks ivirabyan.

model_utils/managers.py

@@ -185,6 +185,9 @@ def create_pass_through_manager_for_queryset_class(base, queryset_cls):
             return queryset_cls(self.model, **kwargs)
 
         def __reduce__(self):
+            # our pickling support breaks for subclasses (e.g. RelatedManager)
+            if self.__class__ is not _PassThroughManager:
+                return super(_PassThroughManager, self).__reduce__()
             return (
                 unpickle_pass_through_manager_for_queryset_class,
                 (base, queryset_cls),

model_utils/tests/tests.py

@@ -608,14 +608,19 @@ class PassThroughManagerTests(TestCase):
 class CreatePassThroughManagerTests(TestCase):
     def setUp(self):
         self.dude = Dude.objects.create(name='El Duderino')
-        Spot.objects.create(name='The Crib', owner=self.dude, closed=True,
-                            secure=True)
 
     def test_reverse_manager(self):
+        Spot.objects.create(
+            name='The Crib', owner=self.dude, closed=True, secure=True)
         self.assertEqual(self.dude.spots_owned.closed().count(), 1)
 
     def test_related_queryset_pickling(self):
+        Spot.objects.create(
+            name='The Crib', owner=self.dude, closed=True, secure=True)
         qs = self.dude.spots_owned.closed()
         pickled_qs = pickle.dumps(qs)
         unpickled_qs = pickle.loads(pickled_qs)
         self.assertEqual(unpickled_qs.secured().count(), 1)
+
+    def test_related_manager_create(self):
+        self.dude.spots_owned.create(name='The Crib', closed=True, secure=True)