On Jul 8, 2008, at 2:04 PM, Manlio Perillo wrote:
>
> I'm thinking to add a function:
>
> # XXX add support for additional parameters like close_with_result?
> def contextual_connect(environ, engine):
> connection = environ.get('wsgix.dbapi.contextual_connection')
> if connection is None:
> connection = engine.connect()
> environ['wsgix.dbapi.contextual_connection'] = connection
>
> return connection
>
>
> Using this function I can do:
>
> connection = contextual_connect(environ, engine)
> engine.transaction(callable, connection, *args, **kwargs)
>
> and so on, perhaps implementing some convenient wrappers.
>
>
> Moreover I plan to write a "pseudo" middleware that will take care of
> proper cleanup of the contextual connection at the end of the request.
>
>
> My question is: will this suffice or should I implement something more
> integrated with SQLAlchemy?
>
>
> Another problem is with the ORM, but I'm still studing it since a lot
> has changed since last time I have used it.
Current integration approaches focus on the scoped_session() construct
as "home base" for the current transaction. This is an adaption of
0.3's "SessionContext", and the idea is the same; it receives a
"scopefunc" which can return any token you like that identifies the
current "context". By default, it returns the current thread
identifier, but you can change it to examine other resources to get at
the WSGI environ or similar. When using ORM session, the automatic
"nesting of begin/commit" behavior is available if you set autocommit
to True to start with, then use "begin()/commit()" pairs, sending the
flag "subtransactions=True" to allow subtransactions. I'm not sure if
your scheme overall calls for that.
I think the method you're using with an individual connection would
work fine as well - the begin() method on connection also nests
itself with a "subtransaction" when called multiple times.
Obviously, if multiple requests occur async in a single thread, you
have to ensure the connection pool is sized appropriately otherwise
your whole app could freeze if an async request blocks on no
connections available.
>
>
>
>
> Thanks Manlio Perillo
>
>
>
> >
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