From 9d83de8ff3b835603fe09e8842529c9810bc1dcd Mon Sep 17 00:00:00 2001
From: Andriy Sokolovskiy <me@asokolovskiy.com>
Date: Fri, 29 May 2015 14:45:36 +0300
Subject: [PATCH] [1.8.x] Fixed #24831 -- Fixed pickling queryset with
 prefetch_related() after deleting objects.

Backport of 2913d6b77d8b2082dc79df5503b7dd3ddd05fcc1 from master
---
 django/db/models/fields/related.py |  5 +++++
 docs/releases/1.8.3.txt            |  3 +++
 tests/queryset_pickle/tests.py     | 14 ++++++++++++++
 3 files changed, 22 insertions(+)

diff --git a/django/db/models/fields/related.py b/django/db/models/fields/related.py
index 6fa46954e0..ddcf5e3e73 100644
--- a/django/db/models/fields/related.py
+++ b/django/db/models/fields/related.py
@@ -1407,6 +1407,11 @@ class ManyToOneRel(ForeignObjectRel):
             parent_link=parent_link, on_delete=on_delete, related_query_name=related_query_name)
         self.field_name = field_name
 
+    def __getstate__(self):
+        state = self.__dict__.copy()
+        state.pop('related_model', None)
+        return state
+
     def get_related_field(self):
         """
         Returns the Field in the 'to' object to which this relationship is
diff --git a/docs/releases/1.8.3.txt b/docs/releases/1.8.3.txt
index c2a4f6af3d..78e6766872 100644
--- a/docs/releases/1.8.3.txt
+++ b/docs/releases/1.8.3.txt
@@ -37,3 +37,6 @@ Bugfixes
 
 * Fixed lack of unique constraint when changing a field from
   ``primary_key=True`` to ``unique=True`` (:ticket:`24893`).
+
+* Fixed queryset pickling when using ``prefetch_related()`` after deleting
+  objects (:ticket:`24831`).
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