Indeed, I do have TaskTags mapped to it's own class. However, I never explicitly delete any TaskTag object, only create them.
In any case, what would the preferred way to add a new tag to a task (a new entry in the association table)? I was using the ORM to just create a new instance of TaskTag (the mapped class). If having the association table mapped to its own class becomes problematic, what's the convention for accomplishing this? Thanks for your feedback :-) -Dave On Wed, Dec 2, 2009 at 4:58 PM, Michael Bayer <mike...@zzzcomputing.com>wrote: > > On Dec 2, 2009, at 5:46 PM, Dave Paola wrote: > > I'm getting this: ConcurrentModificationError: updated rowcount 0 does not > match number of objects updated 1 when I try to commit a simple deletion. > I'm using Sqlite locally but the error also occurs on a Postgres database > in a live environment with only ONE user connected. > > I saw this post from Nov. 11th: > http://groups.google.com/group/sqlalchemy/browse_thread/thread/e7175c7351963128but > because I'm not doing any copying (just deletion), it didn't seem to > provide anything useful. Both session.dirty and session.new are empty. > > I have a Task class mapped to an association table called TaskTag that has > a task_id and tag_id. I'm literally doing a session.delete(task) followed > by a session.commit() and session.close(). Here's my mapper: > > mapper(Task, tasks_table, properties = { > 'tags' : relation(Tag, secondary=tasktags_table, lazy = > False) > }) > > I suspect this has something to do with the many-to-many relationship, but > for the life of me I cannot figure out what's going on. Thanks in advance. > > > this can happen if you have tasktags_table explicitly mapped elsewhere. > the mapper for tasktags_table will issue a DELETE, and then if Task.tags is > also modified in some way that affects the same row, the DELETE issued > corresponding to the relation() will not find its row. In that case the > "Concurrent" name is referring to two different configurations within a > single flush conflicting with each other. If this is your issue, strategies > to address include placing viewonly=True on the relation() or using the > association proxy pattern (you can even use both if you want to pick and > choose how the SQL to load records is emitted). > > P.S. I use SqlAlchemy so often, I love the framework. Thanks to everyone > for your hard work, it's greatly appreciated :-) > > > The compliments are appreciated ! > > > > > -- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To post to this group, send email to sqlalch...@googlegroups.com. > To unsubscribe from this group, send email to > sqlalchemy+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/sqlalchemy?hl=en. > > > -- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To post to this group, send email to sqlalch...@googlegroups.com. > To unsubscribe from this group, send email to > sqlalchemy+unsubscr...@googlegroups.com<sqlalchemy%2bunsubscr...@googlegroups.com> > . > For more options, visit this group at > http://groups.google.com/group/sqlalchemy?hl=en. > -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
