[1.5.x] Fixed prefetch_related + pickle regressions

There were a couple of regressions related to field pickling. The
regressions were introduced by QuerySet._known_related_objects caching.

The regressions aren't present in master, the fix was likely in
f403653cf146384946e5c879ad2a351768ebc226.

Fixed #20157, fixed #20257. Also made QuerySets with model=None
picklable.

2 files changed, 41 insertions, 1 deletions

diff --git a/tests/regressiontests/queryset_pickle/models.py b/tests/regressiontests/queryset_pickle/models.py
index d3500c903b..871fdd8a11 100644
--- a/tests/regressiontests/queryset_pickle/models.py
+++ b/tests/regressiontests/queryset_pickle/models.py
@@ -36,3 +36,16 @@ class Happening(models.Model):
     number2 = models.IntegerField(blank=True, default=Numbers.get_static_number)
     number3 = models.IntegerField(blank=True, default=Numbers.get_class_number)
     number4 = models.IntegerField(blank=True, default=nn.get_member_number)
+
+class Person(models.Model):
+    name = models.CharField(max_length=200)
+
+class SocialProfile(models.Model):
+    person = models.ForeignKey(Person)
+    friends = models.ManyToManyField('self')
+
+class Post(models.Model):
+    post_date = models.DateTimeField(default=datetime.datetime.now)
+
+class Material(models.Model):
+    post = models.ForeignKey(Post, related_name='materials')
diff --git a/tests/regressiontests/queryset_pickle/tests.py b/tests/regressiontests/queryset_pickle/tests.py
index ab32e8f647..19519b2db9 100644
--- a/tests/regressiontests/queryset_pickle/tests.py
+++ b/tests/regressiontests/queryset_pickle/tests.py
@@ -5,7 +5,8 @@ import datetime
 
 from django.test import TestCase
 
-from .models import Group, Event, Happening
+from .models import Group, Event, Happening, Person, Post
+from django.contrib.auth.models import AnonymousUser
 
 
 class PickleabilityTestCase(TestCase):
@@ -46,3 +47,29 @@ class PickleabilityTestCase(TestCase):
         # can't just use assertEqual(original, unpickled)
         self.assertEqual(original.__class__, unpickled.__class__)
         self.assertEqual(original.args, unpickled.args)
+
+    def test_pickle_m2m_prefetch_related(self):
+        bob = Person(name="Bob")
+        bob.save()
+        people = Person.objects.prefetch_related('socialprofile_set')
+        dumped = pickle.dumps(people)
+        people = pickle.loads(dumped)
+        self.assertQuerysetEqual(
+            people, [bob], lambda x: x)
+
+    def test_pickle_field_default_prefetch_related(self):
+        p1 = Post.objects.create()
+        posts = Post.objects.prefetch_related('materials')
+        dumped = pickle.dumps(posts)
+        posts = pickle.loads(dumped)
+        self.assertQuerysetEqual(
+            posts, [p1], lambda x: x)
+
+    def test_pickle_emptyqs(self):
+        u = AnonymousUser()
+        # Use AnonymousUser, as AnonymousUser.groups has qs.model = None
+        empty = u.groups.all()
+        dumped = pickle.dumps(empty)
+        empty = pickle.loads(dumped)
+        self.assertQuerysetEqual(
+            empty, [])