I have detected the sole codepath which does in fact produce the
output you've seen which is also erroneous. That issue is fixed in
r5661. However, the reproduction of the bug is doesn't appear
possible with the scenario you describe, which suggests that your
serialization/merge scheme may still be producing data that is not
what's expected.
The reproduction of the error is via issuing a session.delete() for
the object, then issuing session.add() for a brand new object which
has no values set in the child table, but includes the primary key of
the original object. It is not possible to produce this effect using
merge() since merge() will never result in an INSERT for a primary key
value that already exists in the database or session.
Also, my analysis of the issue also has led me to rethink the feature
in question (called a row switch), so I will almost certainly be
changing the behavior of it once again in 0.6 to issue an explicit
DELETE and INSERT for a delete()/add() pair of the same primary key.
So if we don't figure out how your pickle/merge() scenario is being
interpreted as a delete()/add() pair, this eventual change might again
cause problems for you even if the issue is resolved for now.
On Jan 13, 2009, at 12:03 AM, Michael Bayer wrote:
>
>
> On Jan 12, 2009, at 11:37 PM, Duder wrote:
>> missing from the object, so it is generating bad SQL. Is this a bug,
>> or do I need to change something to be compatible with 0.5.0?
>
>
> its impossible to say without a full reproducing test case. I've
> tried many versions of the test below and none have any issue:
>
> from sqlalchemy import *
> from sqlalchemy.orm import *
> from sqlalchemy.ext.declarative import declarative_base
> import cPickle as pickle
>
> engine = create_engine('sqlite://', echo=True)
> Base = declarative_base()
> class Person(Base):
> __tablename__ = 'people'
> id = Column('id', Integer, primary_key=True)
> name = Column('name', String(50))
> discriminator = Column('type', String(50))
> __mapper_args__ = {'polymorphic_on':discriminator}
>
> class Engineer(Person):
> __tablename__ = 'engineers'
> __mapper_args__ = {'polymorphic_identity':'engineer'}
> id = Column('id', Integer, ForeignKey('people.id'),
> primary_key=True)
> primary_language = Column('primary_language', String(50))
>
> Base.metadata.create_all(engine)
>
> e1 = Engineer(name="dilbert", primary_language="java")
>
> sess = sessionmaker(engine)()
> sess.add(e1)
>
> sess.commit()
>
> e1 = sess.query(Person).filter(Person.name=='dilbert').one()
>
> assert 'primary_language' not in e1.__dict__
> assert 'name' in e1.__dict__
>
> sess.expunge(e1)
>
> # "serialize to the client"
> e2 = pickle.loads(pickle.dumps(e1))
>
> # client changes something (?)
> e2.name = 'ed'
>
> # "deserialize from the client"
> e3 = pickle.loads(pickle.dumps(e2))
>
> # merge
> e1 = sess.merge(e3)
> sess.commit()
>
>
> >
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