Hi, I have two tables User and Following, and User has two relationships followings and followers. It’s so typical, and next I want is readonly relationship to union of followings and followers. I tried like:
friends = relationship( 'User', collection_class=set, primaryjoin='''or_( and_(foreign(User.id) == Following.follower_id, remote(User.id) == Following.followee_id), and_(foreign(User.id) == Following.followee_id, remote(User.id) == Following.follower_id) )''', viewonly=True ) but it seems to no work because foreign_keys and remote_side are the same columns (User.id). The error message is: sqlalchemy.exc.ArgumentError: Can't determine relationship direction for relationship 'User.friends' - foreign key columns within the join condition are present in both the parent and the child's mapped tables. Ensure that only those columns referring to a parent column are marked as foreign, either via the foreign() annotation or via the foreign_keys argument. Basically I want to find how to specify foreign_keys and remote_side in such self-referential many-to-many relationships, but it’s okay if there’re any other ways to implement the same thing. I just need to use such relationship in query expressions e.g. query.filter(User.friends.any(…)), query.options(joinedload(User.friends)) and instance properties e.g. map(make_json, user.friends). (If I implement it using @property decorator it won’t work with query expressions.) I read these two chapters in the docs: http://docs.sqlalchemy.org/en/rel_0_8/orm/relationships.html#self-referential-many-to-many-relationship http://docs.sqlalchemy.org/en/rel_0_8/orm/relationships.html#creating-custom-foreign-conditions Are there any other resources to get more hints about it? Thanks, Hong Minhee -- 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?hl=en. For more options, visit https://groups.google.com/groups/opt_out.