Ticket #3519: ticket3519.diff

django/db/models/manipulators.py

@@ -160 +160 @@
                     # old to the new, to see which fields have changed.
                     old_rel_obj = None
                     if self.change:
-                        if rel_new_data[related.opts.pk.name][0]:
+                        if rel_new_data[related.opts.pk.name] and rel_new_data[related.opts.pk.name][0]:
                             try:
                                 old_rel_obj = getattr(self.original_object, related.get_accessor_name()).get(**{'%s__exact' % related.opts.pk.name: rel_new_data[related.opts.pk.attname][0]})
                             except ObjectDoesNotExist:

django/db/models/fields/__init__.py

@@ -284 +284 @@
         Given the full new_data dictionary (from the manipulator), returns this
         field's data.
         """
-        if rel:
+        if rel and new_data.get(self.name, [self.get_default()]):
             return new_data.get(self.name, [self.get_default()])[0]
         val = new_data.get(self.name, self.get_default())
         if not self.empty_strings_allowed and val == '' and self.null: