Hi Simon,
Thanks for the fast reply.
I tried adding session.add(item) and session.flush() in the else clause in
the past but that didn't solve my problem.
I didn't however remove the merge, do you think that might be the problem?
Regarding the flush, this code is part of an API server where a
scoped_session is committed after each change. I haven't changed the
autoflush parameter, and as I understand the default value is True making a
flush before each commit or query.
As for the UniqueObject recipe, thanks! Amazing that I never found it
searching for a cure. As I see it basically does the same ...
I never managed to reproduce this bug on my development environment. It
only happens in my production environment.
Do you suppose adding a session.add and removing the merge will solve this
issue?
Thanks,
Ofir
On Tuesday, August 27, 2013 3:55:50 PM UTC+3, Simon King wrote:
>
> On Tue, Aug 27, 2013 at 1:40 PM, herzaso <her...@gmail.com <javascript:>>
> wrote:
> > I have a model with an ID column set as the primary key, though i'd like
> to
> > be able to identify records by 3 other columns.
> > For this situation, I've added a classmethod that will fetch the record
> if
> > found or a new record if not.
> > The problem i'm having is that every once in a while, I get
> IntegrityError
> > trying to flush a change
> >
> > class Foo(Base):
> > __table_args__ = (sa.UniqueConstraint('bar', 'baz', 'qux'),)
> >
> > id = sa.Column(Identifier, sa.Sequence('%s_id_seq' % __tablename__),
> > nullable=False, primary_key=True)
> > bar = sa.Column(sa.BigInteger)
> > baz = sa.Column(sa.BigInteger)
> > qux = sa.Column(sa.BigInteger)
> > a1 = sa.Column(sa.BigInteger)
> > a2 = sa.Column(sa.BigInteger)
> >
> > @classmethod
> > def get(cls, bar=None, baz=None, qux=None, **kwargs):
> > item = session.query(cls).\
> > filter(cls.bar== bar).\
> > filter(cls.baz == baz).\
> > filter(cls.qux == qux).\
> > first()
> >
> > if item:
> > for k, v in kwargs.iteritems():
> > if getattr(item, k) != v:
> > setattr(item, k, v)
> > else:
> > item = cls(bar=bar, baz=baz, qux=qux, **kwargs)
> >
> > return item
> >
> > This is the code I use to add/update records:
> >
> > foo = Foo.get(**item)
> > session.merge(foo)
> >
> > I'm struggling with this problem for some time now, and would appreciate
> any
> > help ...
> >
>
> I'm not sure of the exact problem, but there are a couple of things
> that you could investigate.
>
> Firstly, session.merge returns a copy of the object, rather than
> adding the object that you supplied into the session. See
> http://docs.sqlalchemy.org/en/rel_0_8/orm/session.html#merging for
> details.
>
> Secondly, your "get" method sometimes returns objects that are already
> part of the session (if they were in the database), and sometimes
> objects that are not in the session. It would probably be more
> consistent to always return objects that are part of the session, by
> putting "session.add(item)" in your "else" clause. This would get rid
> of the need for session.merge(). (If you want to be able to use the
> "get" with non-global sessions, pass the session as a parameter.)
>
> Finally, if your session isn't auto-flushing, it would be possible for
> you to call "get" twice with the same parameters and get 2 different
> objects back.
>
> You may want to look at the UniqueObject recipe in the wiki:
> http://www.sqlalchemy.org/trac/wiki/UsageRecipes/UniqueObject
>
> Hope that helps,
>
> Simon
>
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