Adrian <adr...@planetcoding.net> wrote:
> @declared_attr > def user(cls): > """The user owning this favorite""" > return db.relationship( > 'User', > lazy=False, > foreign_keys=lambda: [cls.user_id], > backref=db.backref( > '_favorite_users', > lazy=True, > cascade='all, delete-orphan', > primaryjoin=lambda: '(User.id == user_id) & > ~target.is_deleted' > ) > ) the primaryjoin should be either the expression as a Python object (not a string), or a lambda that returns the expression object (not a string), or if you’re using declarative it can be a string that’s eval’ed. But not a lambda *and* a string at the same time. > I've added it on the backref since that's the relationship where I want the > filter to apply. > In the end I'd like to be able to do this: > User.query.get(123)._favorite_users which would get me a list of all the > favorite users (I'll be using association_proxy, but for now I need to get > the relationships themselves working) besides those users who have > is_deleted=True (on the User, not the FavoriteUser). > > But no matter what I put there (tried both lambdas and strings), I always get > this error (so I can't even try to figure out the correct criteria to use, > since it fails early, during mapper configuration time): > sqlalchemy.exc.ArgumentError: Column-based expression object expected for > argument 'primaryjoin'; got: '(User.id == user_id) & ~target.is_deleted', > type <type 'unicode’> yeah that’s the lambda + string together which is not the correct use. > > > Actually.... looking at this code again... it's almost a standard > many-to-many relationship, so I should probably be using secondary and > secondaryjoin somewhere. Can I define this backref-like, i.e. from within the > FavoriteUser model? That way I don't have to spread things around so much > (which would be the case if I defined the relationship in the User model). the model here doesn’t illustrate how this would be a many-to-many. -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
