What you are describing could be solved with inheritance. You would define a base class and table for Orders and properties common to all orders, and then a seperate class/table for each type with properties specific to those types.
Table inheritance is covered in the SA docs, and I think SA can determine what sublcass to use when you load an order - haven't tried this myself though with SA. Arnar On 6/16/06, Koen Bok <[EMAIL PROTECTED]> wrote: > > Maybe a little metaphor to make it more simple. > > Let's say I make houses. The roof of the house can either be concrete or > wood. Concrete and wood come in many types. > > Design: > > House > id > name > > Wood > id > name > treename > > Concrete > id > name > hardness > > Now if I have a House object it should have a roof relation which either > links to a Wood object or a Concrete object. It NEEDS to be linked to one of > them. > > Like this: > > >>> house = session.query(House).get(1) > >>> print house.roof > <Concrete id=123 name=SuperBeautiful hardness=500> > > >>> house = session.query(House).get(2) > >>> print house.roof > < Wood id=321 name=Oak treename='Oak Tree'> > > > > On 16-jun-2006, at 5:24, Michael Bayer wrote: > > > whats wrong with this ? > > order_types > --------------- > type_id > name > from_stock_id > to_stock_id > > ? > > > On Jun 15, 2006, at 6:44 PM, Koen Bok wrote: > > Within my organisation we have orders. Orders move products between three > entities: Suppliers, Stocks and Customers. > > The type of an order gets defined by the origin and the destination it is > moving products. This way we can have the following types of orders: > > > From: To: -> Stock BUYORDER > Stock -> Supplier RETOURBUYORDER > Stock -> Stock INTERNORDER > Stock -> Customer SELLORDER > Customer ! -> Stock RETOURSELLORDER > > How can I design objects/mappers to do this: > > >>> order = session.query(Order).get(1) > >>> print order.type > <Type id=123 name='INTERNORDER' from=<Stock id=2> to=<Stock id=4>> > > >>> order = session.query(Order).get(2) > >>> print order.type > <Type id=456 name='SELLORDER' from=<Stock id=4> to=<Customer id=1928>> > _______________________________________________ > Sqlalchemy-users mailing list > Sqlalchemy-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/sqlalchemy-users > > > > > > _______________________________________________ > Sqlalchemy-users mailing list > Sqlalchemy-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/sqlalchemy-users > > > > _______________________________________________ Sqlalchemy-users mailing list Sqlalchemy-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sqlalchemy-users
