Ticket #6915: 6915.naive-patch.2.diff

django/db/models/query.py

@@ -261 +261 @@
         """
         Deletes the records in the current QuerySet.
         """
-        assert self.query.can_filter(), \
-                "Cannot use 'limit' or 'offset' with delete."
-
         del_query = self._clone()
 
         # Disable non-supported fields.
         del_query.query.select_related = False
         del_query.query.clear_ordering()
 
-        # Delete objects in chunks to prevent the list of related objects from
-        # becoming too long.
-        while 1:
-            # Collect all the objects to be deleted in this chunk, and all the
-            # objects that are related to the objects that are to be deleted.
-            seen_objs = SortedDict()
-            for object in del_query[:CHUNK_SIZE]:
-                object._collect_sub_objects(seen_objs)
-
-            if not seen_objs:
-                break
-            delete_objects(seen_objs)
-
+        # Delete objects individually if self is sliced or self.model has a custom delete() method.
+        # Use a DELETE query otherwise.
+        # See ticket #6915.
+        from django.db.models import Model
+        if not self.query.can_filter() or self.model is not None and self.model.delete != Model.delete:
+            for obj in del_query:
+                obj.delete()
+                
+        else:
+            # Delete objects in chunks to prevent the list of related objects from
+            # becoming too long.
+            while 1:
+                # Collect all the objects to be deleted in this chunk, and all the
+                # objects that are related to the objects that are to be deleted.
+                seen_objs = SortedDict()
+                for object in del_query[:CHUNK_SIZE]:
+                    object._collect_sub_objects(seen_objs)
+    
+                if not seen_objs:
+                    break
+                delete_objects(seen_objs)
+    
         # Clear the result cache, in case this QuerySet gets reused.
         self._result_cache = None
     delete.alters_data = True