On Apr 21, 2012, at 7:06 AM, Moritz Schlarb wrote: > > So basically, a Child object may set it's own value for time, but if it's not > set, it uses the value from its parent. > This works, but I would also like to be able to do something like: > > session.query(Child).filter(Child.parent.another_id==2) > > (Which would throw Neither 'InstrumentedAttribute' object nor 'Comparator' > object has an attribute 'another_id')
SQLAlchemy doesn't implicitly generate joins when you call attributes from relationship-bound attribute (here, Child.parent is a relationship-bound attribute and "another_id" is an attribute you're trying to call from it). instead, you need to think in SQL and tell SQLAlchemy that you'd like to join from Child to Parent: query(Child).join(Child.parent).filter(Parent.another_id==2) joining is covered in the tutorial at http://docs.sqlalchemy.org/en/latest/orm/tutorial.html#querying-with-joins . Also when you do a query from inside of a @property, you might want to use object_session() to get at the Session. A similar example to what you're doing is here: http://docs.sqlalchemy.org/en/latest/orm/relationships.html#building-query-enabled-properties -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
