Ticket #22726: one-to-one.patch

django/db/models/fields/related.py

@@ -230 +230 @@
                 if not router.allow_relation(value, instance):
                     raise ValueError('Cannot assign "%r": the current database router prevents this relation.' % value)
 
-        related_pk = tuple([getattr(instance, field.attname) for field in self.related.field.foreign_related_fields])
-        if None in related_pk:
-            raise ValueError('Cannot assign "%r": "%s" instance isn\'t saved in the database.' %
-                                (value, instance._meta.object_name))
-
+        related_pk = tuple([getattr(instance, field.attname)
+                            for field in self.related.field.foreign_related_fields])
         # Set the value of the related field to the value of the related object's related field
         for index, field in enumerate(self.related.field.local_related_fields):
             setattr(value, field.attname, related_pk[index])

tests/one_to_one_regress/tests.py

@@ -235 +235 @@
     def test_set_reverse_on_unsaved_object(self):
         """
         Writing to the reverse relation on an unsaved object
-        is impossible too.
+        is possible.
         """
         p = Place()
         b = UndergroundBar.objects.create()
         with self.assertNumQueries(0):
-            with self.assertRaises(ValueError):
-                p.undergroundbar = b
+            p.undergroundbar = b
+            self.assertEqual(p.undergroundbar, b)
+            self.assertEqual(b.place, p)
+
+        p2 = Place()
+        b2 = UndergroundBar()
+        with self.assertNumQueries(0):
+            p2.undergroundbar = b2
+            self.assertEqual(p2.undergroundbar, b2)
+            self.assertEqual(b2.place, p2)