Jonathan LaCour wrote:
> I am attempting to model a doubly-linked list, as follows:
Replying to myself:
task_table = Table('task', metadata,
Column('id', Integer, primary_key=True),
Column('name', Unicode),
Column('next_task_id', Integer, ForeignKey('task.id')),
Column('previous_task_id', Integer, ForeignKey('task.id'))
)
class Task(object):
def __init__(self, **kw):
for key, value in kw.items():
setattr(self, key, value)
def __repr__(self):
return '<Task :: %s>' % self.name
mapper(Task, task_table, properties={
'next_task' : relation(
Task,
primaryjoin=task_table.c.next_task_id==task_table.c.id,
uselist=False,
remote_side=task_table.c.id,
backref=backref(
'previous_task',
primaryjoin=task_table.c.previous_task_id==task_table.c.id,
uselist=False
)
),
})
... seems to do the trick. I had tried using backref's earlier,
but it was failing because I was specifying a "remote_side" keyword
argument to the backref(), which was making it blow up with cycle
detection exceptions for some reason.
--
Jonathan LaCour
http://cleverdevil.org
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