On Jan 10, 2012, at 11:38 AM, Josh Ha-Nyung Chung wrote: > I'm running web service using sqlalchemy with apache + wsgi + pyramid > framework. > I've initialize metadata like the following: > > Base = declarative_base() > Base.metadata.reflect(bind=my_engine) > user_table = DP_Base.metadata.tables["user"] > mapper(User, user_table) > > and I'm using scoped session since I'm running apache+wsgi with multiple > processes and threads. > weird thing is that, errors occur sometimes saying > > ArgumentError: Class '<class 'mypackage.User'>' already has a primary mapper > defined. Use non_primary=True to create a non primary Mapper. > clear_mappers() will remove *all* current mappers from all classes. > > Once the error occurs, all the following requests to the web service > encounter the same errors. Restarting httpd seems to resolve the problem > temporarily. > > I'm afraid that I'm using reflection and mapping in the wrong way? or Is > there something that I have to care about among multi-threaded, scoped > session, and table mapping? > >
does User extend Base ? In that case, it's already mapped. Unless you have a real need to use classical mappings there's no need to use mapper() (would be also curious what lead to that decision as it may be a documentation issue). -- 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.
