error when use two-phase transactions and pass connection to session.bind_mapper after session.commit()

[Former user]

Steps to reproduce[BR] 1) I create new two-phase session and bind with bind_mapper(mapper, connectionObject)[BR] 2) session.commit() throws exception[BR]

The problem was in commit function, when it decides to set _ _transaction to None, next piece of code tried to make rollback() and _ _transaction is not instance of TwoPhaseTransaction.[BR]

I've fixed it by ugly hack in sqlalchemy.engine.base

from sqlalchemy.engine.base import Transaction
def close(self):
    if not self._parent.is_active or self.connection._Connection__transaction is None:
        return
    if self._parent is self:
        self.rollback()

Transaction.close = close

When I use engine instead of connection all works

[Mike Bayer]

can you add some detail about the "error" ? is the rollback() somehow disallowed on the connection ? what backend ?

[Former user]

Rollback is allowed in this transaction.[BR] I think problem is in sqlalchemy.engine.base.Transaction.close method[BR] [BR] 1. In session.py after two phase transaction committed {{{t1.commit() #session.py:382}}} in base.Connection {{{self.__transaction}}} became None (base.py:_commit_twophase_impl():790)[BR] 2. session.py call {{{self.close():#session.py:390}}}[BR] 3. In {{{Session.close() # session.py:426}}} will be called {{{transaction.close()}}}, because I use connection instead of engine and autoclose is False[BR] 4. For two phase transactions in close method {{{self._parent is self}}}, so called rollback[BR] 5. Rollback in {{{Connection._rollback_twophase_impl #base.py:780}}} require

But it set None in commit and transaction not started yet

[Mike Bayer]

if you could illustrate with a small sample script that reproduces the error, it would greatly increase the chances of this fix being committed today or tomorrow, otherwise I'll have to find time to reproduce the issue.

[Former user]

from sqlalchemy import create_engine, MetaData, Table
from sqlalchemy.orm import sessionmaker, mapper
import vr.config as config

engine = create_engine("mysql://%(user)s:%(passwd)s@%(host)s/%(db)s" % config.db.COMMON, pool_size=20)

meta = MetaData(engine)
structure = Table("someTable", meta, autoload=True)

class MyTable(object):
    """ Table class """

mapper(MyTable, structure)

connection = engine.connect()

session = sessionmaker(autoflush=True, autocommit=False, expire_on_commit=False, twophase=True)()

session.bind_mapper(MyTable, connection)

t = MyTable()
session.add(t)

session.prepare()
session.commit()

[Mike Bayer]

fixed for 0.5 branch + 0.6 in a69a094db57ab1c6220930274a96457b0c353221 9a746845d0ce5bfd3216f0ae05627687b5116968

[Mike Bayer]

Removing milestone: 0.5.7 (automated comment)