Micahael gave me this advice:
http://groups.google.com/group/sqlalchemy/browse_thread/thread/df6e451855d13a60/386232232434ff92?lnk=gst&q=enrico#386232232434ff92
in which there are two backrefs and I think it's declarative whereas
yours is classical.
On Aug 18, 4:59 am, Ross Vandegrift <r...@kallisti.us> wrote:
> Hi everyone,
>
> Does anyone have a good setup for one-to-one relationships that are
> always symmetric and provide a common property to access the paired
> object? Ie, it's always the case that:
> 1) (x,y) is in the relation iff (y,x) is in the relation.
> 2) x.peer = y
> 3) y.peer = x
>
> Here's the best thing I've come up with so far. It's not perfect -
> for instance, there's no way to query by partner.
>
> class Person(object):
> def _get_partner(self):
> if self.marriage:
> return self.marriage.get_partner_of(self)
> else:
> return None
> partner = property(_get_partner)
>
> class Marriage(object):
> def __init__(self, a, b):
> self.partners = [a, b]
> def get_partner_of(self, a):
> x = list(self.partners)
> x.remove(a)
> return x[0]
>
> person_t = Table('person', metadata,
> Column('id', Integer, primary_key=True),
> Column('marriageid', Integer, ForeignKey('marriage.id')))
> marriage_t = Table('marriage', metadata,
> Column('id', Integer, primary_key=True))
>
> person_m = orm.mapper(Person, person_t)
> marriage_m = orm.mapper(Marriage, marriage_t,
> properties={'partners': orm.relation(Person,
> backref="marriage")})
>
> Ross
>
> --
> Ross Vandegrift
> r...@kallisti.us
>
> "If the fight gets hot, the songs get hotter. If the going gets tough,
> the songs get tougher."
> --Woody Guthrie
>
> signature.asc
> < 1KViewDownload
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