On Aug 18, 2008, at 5:08 AM, Alen Ribic wrote:
> > sql.py > ==================================== > > class SQLAlchemyMiddleware(object): > """ > Middleware for providing clean SQLAlchemy Session objects for each > Request. > """ > def __init__(self, application): > self.application = application > self.__engine = None > > def get_engine(self): > if self.__engine is None: > self.__engine = create_engine( > settings.SQLALCHEMY_DEFAULT_URL, > pool_recycle=3600, > pool_size=20, > echo_pool=True > ) > return self.__engine > > def init_model(self, engine): > """Call before using any of the tables or classes in the > model.""" > sm = orm.sessionmaker(autoflush=True, transactional=True, > bind=engine) > > meta.engine = engine > meta.Session = orm.scoped_session(sm) > > def __call__(self, environ, start_response): > try: > engine = self.get_engine() > self.init_model(engine) > return self.application(environ, start_response) > finally: > if meta.Session is not None: > meta.Session.remove() > The big mistake here is creating a brand new ScopedSession on each request. This is not how ScopedSession was intended to be used; its created, like Engine, once per application. Some details on this pattern are here: http://www.sqlalchemy.org/docs/05/session.html#unitofwork_contextual_lifespan The way you have it, a concurrent thread can easily interrupt the ScopedSession instance attached to "meta" and replace with a new one, with the old one being lost. Here's a more reasonable approach: class SQLAlchemyMiddleware(object): def __init__(self, application): self.application = application meta.engine = create_engine( settings.SQLALCHEMY_DEFAULT_URL, pool_recycle=3600, pool_size=20, echo_pool=True ) meta.Session = orm.scoped_session(orm.sessionmaker(autoflush=True, transactional=True, bind=meta.engine)) def __call__(self, environ, start_response): try: return self.application(environ, start_response) except: meta.Session.rollback() raise finally: meta.Session.remove() --~--~---------~--~----~------------~-------~--~----~ 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 [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---
