Ticket #1816: manipulators.py.diff

manipulators.py

@@ -215 +215 @@
                         # Save many-to-many objects.
                         for f in related.opts.many_to_many:
                             if child_follow.get(f.name, None) and not f.rel.edit_inline:
-                                was_changed = getattr(new_rel_obj, 'set_%s' % f.name)(rel_new_data[f.attname])
+                                # First, clear the existing values.
+                                rel_manager = getattr(new_rel_obj, f.name)
+                                rel_manager.clear()
+                                # Then, set the new values.
+                                for n in rel_new_data[f.attname]:
+                                    rel_manager.add(f.rel.to._default_manager.get(pk=n))
+    
+                                was_changed = True
                                 if self.change and was_changed:
                                     self.fields_changed.append('%s for %s "%s"' % (f.verbose_name, related.opts.verbose_name, new_rel_obj))