On Nov 10, 12:19 pm, Eric Ongerth <ericonge...@gmail.com> wrote: > > Rather than create a specific backref for each subtype of deal, why > not just continue with your basic 'deals' backref, then attach regular > python properties to your Merchant class which return just the desired > "sub-deals". > > Something like: > > class Merchant(object): > ... > @property > def available_deals(self): > return [deal for deal in self.deals if deal.available] > > @property > def expired_deals(self): > return [deal for deal in self.deals if deal.expired] > > ... and so on. >
That's an interesting idea. If I changed the list comprehensions to generators "( deal for deal in self.deals if deal...)" then I might have a winner. > > You could also reverse your order of definition, define Deal first > with no reference to Merchant, then define Merchant second, with > mapper properties for each of your type of deal (probably mapped to > select statements). But I don't know if it would work to have each of > those different mapper properties all use 'merchant' (with, of course, > the uselist=False option to make it 1:1) as the backref identifier. > Yeah, I was thinking something similar. It'd require a lot of work to reorder everything, though. > On Nov 10, 11:19 am, Jonathan Gardner <jgard...@jonathangardner.net> > wrote: > > > I have two tables, merchants and deals. The merchants table is > > represented by Merchant and deals table by Deal. > > > Each merchant can have 0, 1, or many deals. Some of those deals will > > be available, while others will be expired or coming soon or deleted. > > Each deal belongs to exactly one merchant. > > > I'd like to setup Merchant to have attributes "deals", > > "available_deals", "expired_deals", "upcoming_deals", and > > "deleted_deals". These would return, obviously, deals from those > > groups. > > > The twist is that I've spread out my tables and ORM classes across > > several files. I've tried to keep it so that I don't have circular > > dependencies. That means I've defined Merchant first, and then Deal > > later, in separate files > > > It looks like this: > > > in model/merchant.py: > > merchants = Table(...) > > class Merchant(object): ... > > mapper(Merchant, merchants) > > > in model/deal.py: > > deals = Table(...) > > class Deal(object): ... > > mapper(Deal, deals, properties=dict( > > merchant=relationship(Merchant, backref='deals'), > > )) > > > What can I sprinkle in model/deal.py's mapper call to add backrefs to > > 'available_deals', 'deleted_deals', etc...? > > > Or am I going about this all wrong? > > > Thanks in advance. BTW, SQLAlchemy is, by far, the most superior ORM > > in the history of the world, bar none, IMHO. -- 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.
