Hi,
I've run into a rather interesting issue, where calling session.rollback()
dies. The error I get with SQLA 0.7 is:
<class 'sqlalchemy.exc.InvalidRequestError'>: Can't attach instance <Foo at
0x2acf68808710>; another instance with key (<class 'module.Foo'>, (342,)) is
already present in this session.
Traceback:
sqlalchemy-rel_0_7/lib/sqlalchemy/orm/session.py:672:rollback
sqlalchemy-rel_0_7/lib/sqlalchemy/orm/session.py:386:rollback
sqlalchemy-rel_0_7/lib/sqlalchemy/orm/session.py:417:_rollback_impl
sqlalchemy-rel_0_7/lib/sqlalchemy/orm/session.py:274:_restore_snapshot
sqlalchemy-rel_0_7/lib/sqlalchemy/orm/session.py:1620:_update_impl
sqlalchemy-rel_0_7/lib/sqlalchemy/orm/session.py:1648:_attach
0.8 gives a slightly different message, but I think it is essentially the same:
<type 'exceptions.AssertionError'>: A conflicting state is already present in
the identity map for key (<class 'module.Foo'>, (342,))
Traceback:
sqlalchemy-default/lib/sqlalchemy/orm/session.py:637:rollback
sqlalchemy-default/lib/sqlalchemy/orm/session.py:346:rollback
sqlalchemy-default/lib/sqlalchemy/orm/session.py:377:_rollback_impl
sqlalchemy-default/lib/sqlalchemy/orm/session.py:233:_restore_snapshot
sqlalchemy-default/lib/sqlalchemy/orm/session.py:1578:_update_impl
sqlalchemy-default/lib/sqlalchemy/orm/identity.py:115:add
What I see when turning on query logging:
- The Foo object with primary key 342 is loaded (using a non-primary
mapper, if that makes any difference), and then deleted. The session is flushed.
- A new object is created (this time using the primary mapper), and
during INSERT, SQLite assigns the same primary key to it as the previously
deleted object had (I can see that from subsequent SELECT statements
referencing the new object; it would be nice if SQLA logged the primary key
after an INSERT at debug level)
- An application error (unrelated to SQLAlchemy) occurs, which causes
rollback() to be called
I have a reliable reproducer, but it is the unit test of a large application,
so there are lots of possibly unrelated things going on. I've spent two days
coming up with a standalone reproducer, but I've failed, that's why I'm sending
this mail instead of opening a ticket.
Any ideas?
Gabor
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