[1.8.x] Fixed #24831 -- Fixed pickling queryset with prefetch_related() after deleting objects.

Backport of 2913d6b77d8b2082dc79df5503b7dd3ddd05fcc1 from master

1 files changed, 14 insertions, 0 deletions

diff --git a/tests/queryset_pickle/tests.py b/tests/queryset_pickle/tests.py
index 0125c158af..6a3145e29c 100644
--- a/tests/queryset_pickle/tests.py
+++ b/tests/queryset_pickle/tests.py
@@ -120,6 +120,20 @@ class PickleabilityTestCase(TestCase):
         groups = pickle.loads(pickle.dumps(groups))
         self.assertQuerysetEqual(groups, [g], lambda x: x)
 
+    def test_pickle_prefetch_related_with_m2m_and_objects_deletion(self):
+        """
+        #24831 -- Cached properties on ManyToOneRel created in QuerySet.delete()
+        caused subsequent QuerySet pickling to fail.
+        """
+        g = Group.objects.create(name='foo')
+        m2m = M2MModel.objects.create()
+        m2m.groups.add(g)
+        Group.objects.all().delete()
+
+        m2ms = M2MModel.objects.prefetch_related('groups')
+        m2ms = pickle.loads(pickle.dumps(m2ms))
+        self.assertQuerysetEqual(m2ms, [m2m], lambda x: x)
+
     def test_missing_django_version_unpickling(self):
         """
         #21430 -- Verifies a warning is raised for querysets that are