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 [EMAIL PROTECTED] With
> identity
> key (<class '__main__.ExtraStat'>,(u'C',)) conflicts with persistent
> instance [EMAIL PROTECTED]
>
> Thanks!
> Doug
>
> >
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