Re: New instance ExtraStat with identity key (...) conflicts with persistent instance ExtraStat

I've met so few other Farrells, maybe we ARE related!! Get it, related,
in a SqlAlchemy group. Oh man I'm such a geek!!

> -----Original Message-----
> From: sqlalchemy <at> googlegroups.com [mailto:sqlalchemy <at> googlegroups.com]
> On Behalf Of Bob
> Sent: Tuesday, December 02, 2008 9:00 AM
> To: sqlalchemy <at> googlegroups.com
> Subject: [sqlalchemy] Re: New instance ExtraStat with identity key
> (...) conflicts with persistent instance ExtraStat
> 
> 
> I keep thinking one of my relatives has emailed me when you post here
> and I get all excited. Any chance you can change your name ? 
> 
> 2008/12/2 Doug Farrell <dfarrell <at> mypublisher.com>:
> > Michael,
> >
> >
> >
> > Thanks for the pointer, that makes great sense, and once again
points
> how my
> > generally small database design skills. I'll update my code to try
> this out.
> >
> >
> >
> > Again,
> >
> > Thanks!
> >
> > Doug
> >
> >
> >
> > From: sqlalchemy <at> googlegroups.com
> [mailto:sqlalchemy <at> googlegroups.com] On
> > Behalf Of Michael Bayer
> > Sent: Saturday, November 29, 2008 9:28 PM
> > To: sqlalchemy <at> googlegroups.com
> > Subject: [sqlalchemy] Re: New instance ExtraStat with identity key
> (...)
> > conflicts with persistent instance ExtraStat
> >
> >
> >
> > Simon's suggestion about the duplicate "name" still holds.  Your
> relation
> > from Stat->ExtraStat currently needs to be one-to-one since you
> cannot have
> > more than one ExtraStat referencing a single Stat, due to the PK
> constraint
> > on ExtraStat.name.  The error is raising at the point of query()
> since
> > autoflush is kicking in - use session.flush() to isolate the error.
> >
> >
> >
> > On Nov 29, 2008, at 12:18 PM, Doug Farrell wrote:
> >
> > Hi all,
> >
> >
> >
> > I'm having a problem with a new instance of a relation conflicting
> with
> >
> > an existing instance. I'm using SA 0.5rc with Sqlite3. Here are my
> >
> > simplified classes:
> >
> >
> >
> > class Stat(sqladb.Base):
> >
> >      __tablename__ = "stats"
> >
> >      name         = Column(String(32), primary_key=True)
> >
> >      total        = Column(Integer)
> >
> >      created      = Column(DateTime,
default=datetime.datetime.now())
> >
> >      updated      = Column(DateTime)
> >
> >      states       = Column(PickleType, default={})
> >
> >      extraStats   = relation("ExtraStat", backref="stat")
> >
> >
> >
> > class ExtraStat(sqladb.Base):
> >
> >      __tablename__ = "extrastats"
> >
> >      name         = Column(String(32), ForeignKey("stats.name"),
> > primary_key=True)
> >
> >      total        = Column(Integer)
> >
> >      created      = Column(DateTime,
default=datetime.datetime.now())
> >
> >      updated      = Column(DateTime)
> >
> >      states       = Column(PickleType, default={})
> >
> >
> >
> > The above Stat class has a one-to-many relationship with the
> ExtraStat
> >
> > class (which I think I've implemented correctly). Later in the
> >
> > program I create an in memory data model that has as part of it's
> >
> > components two
> >
> > dictionaries that contain Stat instances. Those Stat instances have
> >
> > relationships to ExtraStat instances. My problem comes in the
> >
> > following when I'm trying to update the data in those
> instances/tables.
> >
> > Here is a section of code that throws the exception:
> >
> >
> >
> >
> >
> >
> >
> > pressName = "press%s" % pressNum
> >
> > # add new ExtraStat instances as relations
> >
> > self._addProductStatsPress(productType, pressName)
> >
> > self._addPressStatsProduct(pressName, productType)
> >
> > try:
> >
> >    extraStat = session.query(Stat). \
> >
> >                filter(Stat.name==productType). \
> >
> >                join("extraStats"). \
> >
> >                filter(ExtraStat.name==pressName).one()
> >
> > except:
> >
> >    extraStat = ExtraStat(pressName, ExtraStat.PRESS_TYPE)
> >
> >    self.productStats[productType].extraStats.append(extraStat)
> >
> >    extraStat.states.setdefault(sstate, 0)
> >
> >    extraStat.states[sstate] += 1
> >
> >    extraStat.updated = now
> >
> >    extraStat = session.merge(extraStat)
> >
> > try:
> >
> >    extraStat = session.query(Stat). \
> >
> >                filter(Stat.name==pressName). \
> >
> >                join("extraStats"). \
> >
> >                filter(ExtraStat.name==productType).one()   <====
> throws
> > exception right here
> >
> > except:
> >
> >    extraStat = ExtraStat(productType, ExtraStat.PRODUCT_TYPE)
> >
> >    self.pressStats[pressName].extraStats.append(extraStat)
> >
> >    extraStat.states.setdefault(sstate, 0)
> >
> >    extraStat.states[sstate] += 1
> >
> >    extraStat.updated = now
> >
> >
> >
> > The marked area is wear it throws the exception. I'm not sure what
to
> >
> > do here to get past this, any help or ideas would be greatly
> >
> > appreciated.
> >
> >
> >
> > The exact exception is as follows:
> >
> > Sqlalchemy.orm.exc.FlushError: New instance ExtraStat <at> ... With
> identity
> >
> > key (<class '__main__.ExtraStat'>,(u'C',)) conflicts with persistent
> >
> > instance ExtraStat <at> ...
> >
> >
> >
> > Thanks!
> >
> > Doug
> >
> >
> >
> >
> >
> > >
> >
> 
> > 
> r more options, visit this group at
> http://groups.google.com/group/sqlalchemy?hl=en
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