Ticket #3727: newforms_save_instance.diff

django/newforms/models.py

@@ -36 +36 @@
         raise ValueError("The %s could not be changed because the data didn't validate." % opts.object_name)
     clean_data = form.clean_data
     for f in opts.fields:
-        if not f.editable or isinstance(f, models.AutoField):
+        if not f.editable or isinstance(f, models.AutoField) \
+           or f.name not in clean_data:
             continue
         setattr(instance, f.name, clean_data[f.name])
     if commit: