On Jul 29, 2010, at 2:31 PM, Kent wrote: > I'm getting a messy error that could be a bug, but is very likely > related to my setup of a set of 2 polymorphic classes I am attempting > to map. > > One entity is a "transaction" and the other is a "transaction_archive" > record. The table structure is therefore very similar for both tables > and it seems to fit Concrete Table Inheritance, except there is no > 'parent' entity. Rather, they are sister tables. > > What I have mostly works until I get into loading this union as a > relation to another table... then I'm having problems. > > I couldn't clearly see the "correct" way to set up this when there is > no real inheritance, but rather sister entities. > > Can you suggest how to correctly map these 2 tables?
it looks fine to me except you're asking for eager loading, and if you're querying from the ArTranBase you'd need to specify relationship() at that level (as well as on each child). Example at http://www.sqlalchemy.org/docs/mappers.html#using-relationships-with-inheritance . OTOH if you are not querying from ArTranBase, remove the usage of concrete inheritance altogether. > > ================================================ > artran_union = polymorphic_union({ > 'artran': artrans_table, > 'archive': artransarchive_table > }, 'type', 'artran_union') > > artranbase_mapper = mapper(ArTranBase, artran_union, > with_polymorphic=('*', artran_union), > polymorphic_on=artran_union.c.type, > polymorphic_identity='ignored') > > > # ---------------------------- ArTran > --------------------------------------- # > mapper(ArTran, artrans_table, inherits=artranbase_mapper, > concrete=True, polymorphic_identity='artran', > properties={'trancode': relation(TranCode, > cascade='refresh-expire,expunge', lazy=False), > 'paymenttype': relation(PaymentType, > cascade='refresh-expire,expunge', lazy=False)} > ) > > > # ---------------------------- ArTranArchive > --------------------------------------- # > mapper(ArTranArchive, artransarchive_table, > inherits=artranbase_mapper, > concrete=True, polymorphic_identity='archive', > properties={'trancode': relation(TranCode, > cascade='refresh-expire,expunge', lazy=False), > 'paymenttype': relation(PaymentType, > cascade='refresh-expire,expunge', lazy=False)} > ) > > Thanks in advance. > > -- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To post to this group, send email to sqlalch...@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. > -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalch...@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.
