Sorry, assume instead of class Order, I've got class Product(object): pass
On Feb 26, 1:48 pm, Kent <k...@retailarchitects.com> wrote: > I'm certain sqlalchemy's got a function call in its guts that I was > about to recreate from scratch, so I'm hoping you can spare me the > trouble. > > I'm trying to construct the foreign key where clause and from clause > needed to populate a relation. > > I'd explain how I got here, but might take several days, so instead, > is there a function call to help me? > > In other words, I've got an object, for example an order: > > =================================== > > orderdetail_table = Table("orderdetails",metadata, > Column("orderid", Unicode, ForeignKey('orders.orderid'), > primary_key=True), > Column("lineid", Integer, primary_key=True), > Column("saleprice", Numeric, nullable=False), > Column("productid", Unicode(255), > ForeignKey('products.productid'), nullable=False) > ) > > product_table = Table("products", metadata, > Column("productid", Unicode(255), primary_key=True), > Column("brand", Unicode(255), > ... > ) > > class Order(object): > pass > > class OrderDetail(object): > pass > > # ---------------------------- OrderDetail > -------------------------------------------------------- # > orderdetail_mapper = mapper(OrderDetail, orderdetail_table, > allow_null_pks=False, > properties=dict(product=relation(Product, > cascade='refresh-expire,expunge', #don't save > changes to Product > lazy=False))) > > ===================== > > Say the 'product' relation is not populated on a *transient* > OrderDetail object that I will not be issuing a session flush() for > (there are errors detected.. but that's the long story). > > I want to populate the transient OrderDetails 'product' attribute with > the detached product. > > I assume there is no way a refresh of the 'product' attribute will > accomplish this since the parent obj is transient (which would really > be what I want), so I am also assuming I'll need to build the pk > clause and issue a session.query.get(). > > Since this is dynamic code (accepting any sqla object), I need to > dynamically construct that pk clause and from clause based on the > mapper's RelationProperty. In other words, use _foreign_keys to > construct this ? > > But I imagine there is already a function call that will get me what I > want. > > In the end, for this example, I'd want to dynamically build > session.query(Product).filter( * pk clause based on fks *) > > Is there a function that can get me most everything I want (return the > pk clause) or must I build that up myself, and if myself, do you > recommend the RelationProperty's _foreign_keys attribute as the > starting point? > > Thanks in advance, again. -- 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.