On Feb 13, 2010, at 7:05 PM, Kent wrote:
>
> # want to do more queries and change more, so set autoflush to False
> DBSession.autoflush = False
yeah sorry here, "autoflush" isn't propagated in 0.5.8 to the actual session
when using scoped_session(). That was fixed in 0.6. Here you'd say
DBSession().autoflush = False.
>
> #however the following still causes flush
> rules=DBSession.query(Order).all()
>
> merged.ordersite=u'AA'
>
> #now is when I really want to do the flush
> DBSession.flush()
>
>
> =============================================
> (Output below)
>
>
> As a work-around I can instantiate a new session, but I didn't want
> more sessions than I need and I am not sure at what point I would
> dispose of the extra session (do I just .close() it after my queries?)
>
> It seems more efficient to use the same session the turbogears
> framework has set up... is that the case or can I create and close
> sessions often without concern of efficiency? If I fail to close
> them, do they tie up database resources?
>
> In general, autoflush staying on is fine, so I'd rather turn autoflush
> off and back on when I am finished with certain transactions where I
> know I want it off. Maybe I'll turn autoflush off in the
> sessionmaker, which seems to work, but I still wonder:
>
> Am I doing something wrong? What is my best workaround?
>
>
> Output:
>>>>
>>>>
>>>>
>>>> from sqlalchemy import *
>>>> from sqlalchemy.orm import *
>>>> from zope.sqlalchemy import ZopeTransactionExtension
>>>>
>>>>
>>>> engine =
>>>> create_engine('postgres://user:p...@localhost:5444/name',echo=True)
>>>> metadata = MetaData()
>>>> maker = sessionmaker(bind=engine, autoflush=True, autocommit=False,
> ... extension=ZopeTransactionExtension())
>>>> DBSession = scoped_session(maker)
>>>>
>>>>
>>>> order_table = Table("orders", metadata,
> ... Column("orderid", Unicode, primary_key=True),
> ... Column("ordersite", Unicode)
> ... )
>>>>
>>>> class Order(object):
> ... pass
> ...
>>>> order_mapper = mapper(Order, order_table)
>>>>
>>>>
>>>> o=Order()
>>>> o.orderid = u'SALE25863' #this order exists in the database
>>>> o.ordersite = u'00'
>>>>
>>>> merged=DBSession.merge(o)
> 2010-02-13 06:48:46,816 INFO sqlalchemy.engine.base.Engine.0x...2510
> BEGIN
> 2010-02-13 06:48:46,820 INFO sqlalchemy.engine.base.Engine.0x...2510
> SELECT orders.orderid AS orders_orderid, orders.ordersite AS
> orders_ordersite
> FROM orders
> WHERE orders.orderid = %(param_1)s
> 2010-02-13 06:48:46,820 INFO sqlalchemy.engine.base.Engine.0x...2510
> {'param_1': 'SALE25863'}
>>>>
>>>> # want to do more queries and change more, so set autoflush to False
> ... DBSession.autoflush = False
>>>>
>>>>
>>>> #however the following still causes flush
> ... rules=DBSession.query(Order).all()
> 2010-02-13 06:48:54,620 INFO sqlalchemy.engine.base.Engine.0x...2510
> UPDATE orders SET ordersite=%(ordersite)s WHERE orders.orderid = %
> (orders_orderid)s
> 2010-02-13 06:48:54,620 INFO sqlalchemy.engine.base.Engine.0x...2510
> {'ordersite': '00', 'orders_orderid': 'SALE25863'}
> 2010-02-13 06:48:54,622 INFO sqlalchemy.engine.base.Engine.0x...2510
> SELECT orders.orderid AS orders_orderid, orders.ordersite AS
> orders_ordersite
> FROM orders
> 2010-02-13 06:48:54,622 INFO sqlalchemy.engine.base.Engine.0x...2510
> {}
>>>>
>>>>
>>>> merged.ordersite=u'AA'
>>>>
>>>>
>>>> #now is when I really want to do the flush
> ... DBSession.flush()
> 2010-02-13 06:49:23,429 INFO sqlalchemy.engine.base.Engine.0x...2510
> UPDATE orders SET ordersite=%(ordersite)s WHERE orders.orderid = %
> (orders_orderid)s
> 2010-02-13 06:49:23,429 INFO sqlalchemy.engine.base.Engine.0x...2510
> {'ordersite': 'AA', 'orders_orderid': 'SALE25863'}
>>>>
>>>>
>>>>
>
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