Merge pull request #1032 from yprez/writable-nested-modelserializer_fixes

Writable nested serializer - fix setting nested serializer to null

rest_framework/serializers.py

@@ -891,6 +891,7 @@ class ModelSerializer(Serializer):
             # Nested relationships need to be saved before we can save the
             # parent instance.
             for field_name, sub_object in obj._nested_forward_relations.items():
+                if sub_object:
                     self.save_object(sub_object)
                 setattr(obj, field_name, sub_object)
 

rest_framework/tests/test_relations_nested.py

@@ -10,7 +10,8 @@ class OneToOneTarget(models.Model):
 
 class OneToOneSource(models.Model):
     name = models.CharField(max_length=100)
-    target = models.OneToOneField(OneToOneTarget, related_name='source')
+    target = models.OneToOneField(OneToOneTarget, related_name='source',
+                                  null=True, blank=True)
 
 
 class OneToManyTarget(models.Model):
@@ -179,6 +180,25 @@ class ForwardNestedOneToOneTests(TestCase):
         ]
         self.assertEqual(serializer.data, expected)
 
+    def test_one_to_one_update_to_null(self):
+        data = {'id': 3, 'name': 'source-3-updated', 'target': None}
+        instance = OneToOneSource.objects.get(pk=3)
+        serializer = self.Serializer(instance, data=data)
+        self.assertTrue(serializer.is_valid())
+        obj = serializer.save()
+
+        self.assertEqual(serializer.data, data)
+        self.assertEqual(obj.name, 'source-3-updated')
+        self.assertEqual(obj.target, None)
+
+        queryset = OneToOneSource.objects.all()
+        serializer = self.Serializer(queryset, many=True)
+        expected = [
+            {'id': 1, 'name': 'source-1', 'target': {'id': 1, 'name': 'target-1'}},
+            {'id': 2, 'name': 'source-2', 'target': {'id': 2, 'name': 'target-2'}},
+            {'id': 3, 'name': 'source-3-updated', 'target': None}
+        ]
+        self.assertEqual(serializer.data, expected)
 
     # TODO: Nullable 1-1 tests
     # def test_one_to_one_delete(self):