On Nov 15, 2011, at 8:54 PM, Alex Grönholm wrote: > query = session.query(Z, A.name).outerjoin(Z.b).filter(Z.id == 1) > print query > > # WORKAROUND: > # query = session.query(Z, A.name).outerjoin(Z.b).filter(Z.id == 1) > # ^- use the superclass instead
I'd note that these two queries are written exactly the same, and I'd assume the first one intends to ask for "B.name". If you're telling the ORM that you'd like "B" objects, the WHERE criterion is added (which in a significant plurality of cases is necessary), since it would be invalid to return rows that are of type A but not of type B, i.e. those where the value of "disc" is not 'b'. In this case, the outerjoin to Z.b also adds this same criteria to the ON clause, thereby making the WHERE redundant but because its an outer join also affecting the results, thus escalating it to "erroneous". SQLAlchemy can't however figure out that the outer join elsewhere in the query is sufficient in order to apply the necessary limiting of rows. Its a bug (ticket http://www.sqlalchemy.org/trac/ticket/2328) but unfortunately it's extremely difficult to track and correlate these two conditions accurately, else it would already be doing so. -- 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.
