- Fixed bug in ordering list where the order of items would be

thrown off during a collection replace event, if the
reorder_on_append flag were set to True.  The fix ensures that the
ordering list only impacts the list that is explicitly associated
with the object.
fixes #3191

1 files changed, 10 insertions, 0 deletions

diff --git a/lib/sqlalchemy/orm/collections.py b/lib/sqlalchemy/orm/collections.py
index 1fc0873bd..c2754d58f 100644
--- a/lib/sqlalchemy/orm/collections.py
+++ b/lib/sqlalchemy/orm/collections.py
@@ -589,6 +589,16 @@ class CollectionAdapter(object):
         "The entity collection being adapted."
         return self._data()
 
+    @property
+    def _referenced_by_owner(self):
+        """return True if the owner state still refers to this collection.
+
+        This will return False within a bulk replace operation,
+        where this collection is the one being replaced.
+
+        """
+        return self.owner_state.dict[self._key] is self._data()
+
     @util.memoized_property
     def attr(self):
         return self.owner_state.manager[self._key].impl