In upgrading to 0.6.0 I've found a regression in behavior for
relationships with backrefs that require post_update=True.
from sqlalchemy import Table, Column, Integer, String, MetaData,
create_engine, ForeignKey, ForeignKeyConstraint
from sqlalchemy.orm import relation, sessionmaker, scoped_session,
synonym, object_session, mapper, backref
engine = create_engine('sqlite:///', echo=False)
Session = scoped_session(sessionmaker(autoflush=True,
autocommit=False, bind=engine))
metadata = MetaData()
contacts = Table('contacts', metadata,
Column('id', Integer, primary_key=True),
Column('name', String(35)),
Column('account_id', Integer),
ForeignKeyConstraint(['account_id'], ['accounts.id']))
accounts = Table('accounts', metadata,
Column('id', Integer, primary_key=True),
Column('name', String(35)),
Column('created_by_id', Integer),
ForeignKeyConstraint(['created_by_id'],
['contacts.id'], name='fk1', use_alter=True))
class Contact(object): pass
class Account(object): pass
mapper(Contact, contacts, properties={
'account': relation(Account,
primaryjoin=contacts.c.account_id==accounts.c.id,
post_update=True,
#backref=backref('contacts', post_update=True)
backref='contacts'
)
})
mapper(Account, accounts, properties={
'created_by': relation(Contact,
primaryjoin=accounts.c.created_by_id==contacts.c.id),
#'contacts': relation(Contact,
primaryjoin=accounts.c.id==contacts.c.account_id)
})
metadata.create_all(bind=engine)
# create basic data
frank = Contact()
frank.name = "Frank"
Session.add(frank)
finc = Account()
finc.name = "Frank Inc."
frank.account = finc
Session.add(finc)
Session.commit()
Session.expunge_all()
# reproduce the problem
bob = Contact()
bob.name = 'Bob'
Session.add(bob)
frank = Session.query(Contact).filter_by(name='Frank').first()
finc = frank.account
bob.account = finc
assert bob.account == finc
Session.commit()
assert bob.account == finc
If either backref on the 'account' relation of Contact is set then the
UPDATE fails to issue. If the 'contacts' relation is defined directly
on Account or the backref isn't defined at all then everything works
as expected. This is tested on SQLAlchemy 0.6.0 with Python 2.6. I
verified this as working under 0.5.8.
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