[sqlalchemy] Re: sqlalchemy.exc.InvalidRequestError: Object 'Foo at 0x23b0690' is already attached to session '29012560' (this is '30924944')
On Sun, May 31, 2009 at 16:50, Michael Bayer mike...@zzzcomputing.com wrote: On May 30, 2009, at 1:56 AM, ericthompso...@gmail.com wrote: Upon reaching the instantiation of Foo, my code blows up with the error message in the subject. Now I realize this is often caused by threading issues - multiple threads, each with their own Session, trying to touch an entity without first merging that entity into the thread's local session. But my application is single-threaded and to the best of my knowledge I'm not creating any new sessions other than the ScopedSession that was created when I imported elixir. Even if I had attempted to create several sessions via elixir_session(), my understanding is that I would have been returned the same session because I haven't changed threads and elixir by default uses a ScopedSession. that is all correct. So why is Foo winding up in a new session (and how did it already get attached to my current session)? I haven't passed any options regarding the session in my entity definitions. I can't see anything here which would cause this. A frequent cause of this confusion is when a library makes use of the ScopedSession.mapper method which has the effect of objects being automatically added to a session without the need to say session.add(object) - but again confusion would only occur here if there is more han one session in use. FWIW, this is the case with Elixir by default. You can turn that behavior off if you want though. That explains why your new object gets attached to the current session as soon as you instanciate your class. I have no idea why it is using a different session though. -- Gaëtan de Menten http://openhex.org --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@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 -~--~~~~--~~--~--~---
[sqlalchemy] Re: sqlalchemy.exc.InvalidRequestError: Object 'Foo at 0x23b0690' is already attached to session '29012560' (this is '30924944')
On May 30, 2009, at 1:56 AM, ericthompso...@gmail.com wrote: Upon reaching the instantiation of Foo, my code blows up with the error message in the subject. Now I realize this is often caused by threading issues - multiple threads, each with their own Session, trying to touch an entity without first merging that entity into the thread's local session. But my application is single-threaded and to the best of my knowledge I'm not creating any new sessions other than the ScopedSession that was created when I imported elixir. Even if I had attempted to create several sessions via elixir_session(), my understanding is that I would have been returned the same session because I haven't changed threads and elixir by default uses a ScopedSession. that is all correct. So why is Foo winding up in a new session (and how did it already get attached to my current session)? I haven't passed any options regarding the session in my entity definitions. I can't see anything here which would cause this.A frequent cause of this confusion is when a library makes use of the ScopedSession.mapper method which has the effect of objects being automatically added to a session without the need to say session.add(object) - but again confusion would only occur here if there is more han one session in use. On a somewhat related note, why does Session have so many class methods? It's perplexing to me that I can do things like elixir_session.query(Foo).all() and also elixir_session().query (Foo).all(). I've tried digging through Elixir's entity.py and SQLAlchemy's session.py but I didn't get much out of my first couple of reads. its the ScopedSession you're dealing with.The methods are not class methods, as ScopedSession is instantiated. for every public Session method, the ScopedSession implements a proxying method which will invoke that method upon a Session pulled from a threading.local() object. To access the Session stored in the threading.local() directly, ScopedSession implements __call__(). --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@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 -~--~~~~--~~--~--~---
