From 14d2bb074cccdec32bd26a89353c30fd512b2aa2 Mon Sep 17 00:00:00 2001
From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Wed, 10 Sep 2014 14:14:50 -0400
Subject: - 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

---
 lib/sqlalchemy/ext/orderinglist.py |  7 +++++--
 lib/sqlalchemy/orm/collections.py  | 10 ++++++++++
 2 files changed, 15 insertions(+), 2 deletions(-)

(limited to 'lib/sqlalchemy')

diff --git a/lib/sqlalchemy/ext/orderinglist.py b/lib/sqlalchemy/ext/orderinglist.py
index 67fda44c4..61155731c 100644
--- a/lib/sqlalchemy/ext/orderinglist.py
+++ b/lib/sqlalchemy/ext/orderinglist.py
@@ -119,7 +119,7 @@ start numbering at 1 or some other integer, provide ``count_from=1``.
 
 
 """
-from ..orm.collections import collection
+from ..orm.collections import collection, collection_adapter
 from .. import util
 
 __all__ = ['ordering_list']
@@ -319,7 +319,10 @@ class OrderingList(list):
 
     def remove(self, entity):
         super(OrderingList, self).remove(entity)
-        self._reorder()
+
+        adapter = collection_adapter(self)
+        if adapter and adapter._referenced_by_owner:
+            self._reorder()
 
     def pop(self, index=-1):
         entity = super(OrderingList, self).pop(index)
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
-- 
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