[1.4.X] Fixed #18090 -- Applied filters when running prefetch_related…

… backwards through a one-to-one relation. Backport of r17888 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.4.X@17889 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/fields/related.py

@@ -239,7 +239,7 @@ def get_query_set(self, **db_hints):
     def get_prefetch_query_set(self, instances):
         vals = set(instance._get_pk_val() for instance in instances)
         params = {'%s__pk__in' % self.related.field.name: vals}
-        return (self.get_query_set(instance=instances[0]),
+        return (self.get_query_set(instance=instances[0]).filter(**params),
                 attrgetter(self.related.field.attname),
                 lambda obj: obj._get_pk_val(),
                 True,

tests/modeltests/prefetch_related/tests.py

@@ -1,7 +1,9 @@
 from __future__ import with_statement, absolute_import
 
 from django.contrib.contenttypes.models import ContentType
+from django.db import connection
 from django.test import TestCase
+from django.test.utils import override_settings
 
 from .models import (Author, Book, Reader, Qualification, Teacher, Department,
     TaggedItem, Bookmark, AuthorAddress, FavoriteAuthors, AuthorWithAge,
@@ -356,10 +358,15 @@ def test_parent_link_prefetch(self):
         with self.assertNumQueries(2):
             [a.author for a in AuthorWithAge.objects.prefetch_related('author')]
 
+    @override_settings(DEBUG=True)
     def test_child_link_prefetch(self):
         with self.assertNumQueries(2):
             l = [a.authorwithage for a in Author.objects.prefetch_related('authorwithage')]
 
+        # Regression for #18090: the prefetching query must include an IN clause.
+        self.assertIn('authorwithage', connection.queries[-1]['sql'])
+        self.assertIn(' IN ', connection.queries[-1]['sql'])
+
         self.assertEqual(l, [a.authorwithage for a in Author.objects.all()])