- # problem with RelationMember is that it may link to any one
- # object (a node, a way, another relation), and belongs_to is
- # not flexible enough for that. So we do this, which is ugly,
- # but fortunately rails won't actually run the SQL behind that
- # unless someone really accesses .node, .way, or
- # .relation - which is what we do below based on member_type.
- # (and no: the :condition on belongs_to doesn't work here as
- # it is a condition on the *referenced* object not the
- # *referencing* object!)
-
- belongs_to :node, :foreign_key => "member_id"
- belongs_to :way, :foreign_key => "member_id"
- belongs_to :relation, :foreign_key => "member_id"
-
- # so we define this "member" function that returns whatever it
- # is.
-
- def member()
- return (member_type == "node") ? node : (member_type == "way") ? way : relation
- end
-
- # NOTE - relations are SUBJECTS of memberships. The fact that nodes,
- # ways, and relations can be the OBJECT of a membership,
- # i.e. a node/way/relation can be referenced throgh a
- # RelationMember object, is NOT modelled in rails, i.e. these links
- # have to be resolved manually, on demand.