setting child backref attribute failed when lazy=None

[Former user]

SA version 0.3.10.

In my case a mapper of a parent object specifies lazy=None, and a backref attribute for a child object. Then when I tries to set this attribute of a child object the exception occurs. I guess it is because parent didn't setup the list of child objects.

Also, in some previous version of SA this approach works fine.

[Former user]

Please unpack, cd sched, then issue ./sched.sh

[Mike Bayer]

the posted test case is too long and involved...pls confirm this is the failing condition:

from sqlalchemy import *
from sqlalchemy.orm import *
from sqlalchemy import types

engine = create_engine('sqlite://', echo=True)

metadata = MetaData(engine)

users = Table('users', metadata,
    Column('id', types.Integer, primary_key=True),
    Column('name', types.String(30), nullable=False),
    Column('password', types.String(15))
)

addresses = Table('addresses', metadata,
    Column('id', types.Integer, primary_key=True),
    Column('user_id', types.Integer,
         ForeignKey('users.id'), nullable=False),
    Column('email_address', types.String(100),
         nullable=False)
)

metadata.create_all()

class User(object):
    def __init__(self, name, password):
        self.name = name
        self.password = password

    def __repr__(self):
        return "User(%r, %r)" % (self.name, self.password)


class Address(object):
    def __init__(self, email_address):
        self.email_address = email_address

    def __repr__(self):
        return "Address(%r)" % self.email_address

mapper(User, users, properties={
    'addresses':relation(Address, backref='user', lazy=None)
})
mapper(Address, addresses)

sess = create_session()

# try it on unsaved objects
u1 = User('u1', 'foo')
a1 = Address('a1')
a1.user = u1
sess.save(u1)
sess.flush()
sess.clear()

a1 = sess.query(Address).get(a1.id)

a1.user = None

[Former user]

Replying to zzzeek:

the posted test case is too long and involved...pls confirm this is the failing condition:

Yes, this is the one. The stack trace is below:

Traceback (most recent call last):
  File "./tmp.py", line 60, in ?
    a1.user = None
  File "/usr/lib/python2.4/site-packages/sqlalchemy/orm/attributes.py", line 45, in __set__
    self.set(None, obj, value)
  File "/usr/lib/python2.4/site-packages/sqlalchemy/orm/attributes.py", line 271, in set
    ext.set(event or self, obj, value, old)
  File "/usr/lib/python2.4/site-packages/sqlalchemy/orm/attributes.py", line 646, in set
    getattr(oldchild.__class__, self.key).remove(event, oldchild, obj)
  File "/usr/lib/python2.4/site-packages/sqlalchemy/orm/attributes.py", line 332, in remove
    self.get(obj).remove_with_event(value, event)
  File "/usr/lib/python2.4/site-packages/sqlalchemy/orm/attributes.py", line 516, in remove_with_event
    self.data.remove(item)
ValueError: list.remove(x): x not in list

Thanks.

[Mike Bayer]

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