[sqlalchemy] Re: association proxy error: stale association proxy - Paul K - com.googlegroups.sqlalchemy

4 messages in com.googlegroups.sqlalchemy[sqlalchemy] Re: association proxy er...

From	Sent On	Attachments
Paul K	29 Apr 2008 09:01
Paul K	29 Apr 2008 09:08
jason kirtland	29 Apr 2008 11:49
Paul K	29 Apr 2008 13:43

Subject:	[sqlalchemy] Re: association proxy error: stale association proxy
From:	Paul K (paul...@gmail.com)
Date:	04/29/2008 01:43:55 PM
List:	com.googlegroups.sqlalchemy

Thanks. That fixed what I was seeing.

Paul Kippes

On Apr 29, 1:49 pm, jason kirtland <j....@discorporate.us> wrote:

Paul K wrote:

The following code duplicates a situation I'm seeing with the association proxy. There are at least two ways I can avoid having the error happen. But since I wasn't sure if the error is a usage error, I wanted to post here first before implementing my work around. One work around for the test code is to delete/comment out line 77 (commented as such). I understand why I'm seeing the error. But should the user really be required to keep the parent around in a variable? I would have thought that the session would be tracking each successive changes.

This is fixed in the trunk @ r4593. The issue was in association proxy's handling of a stale cache attribute it stashes on instances and was fundamentally:

p_copy = copy.copy(parent) del parent p_copy.kids.append(a_kid) # previously, boom

That's similar to what was going under the orm hood with the modified instances coming in and out of scope in have_a_kid.

The patch in the trunk is pretty small, but if that's not an option you can work around the issue somewhat painfully by removing the cache attribute from instances:

for attr in dir(p_copy): if attr.startswith('_AssociationProxy_kid_associations_'): delattr(p_copy, attr)