I think it's a good idea, if Mike agrees then I will submit a patch to do this later today. (Except MyClass.my_prop and my_prop_name won't be equiv, you'll have to have whatever your property returns support __eq__)
On Nov 20, 4:37 am, "Gaetan de Menten" <[EMAIL PROTECTED]> wrote: > Hi people, > > I have some classes with "standard python" properties which target > another python object and also uses several columns in the database. I > also got a global factory function to create an instance of that > target object out of the value of the columns (the class of that > target object can vary). > > Now, I'd like to use those properties in filter criteria, as so: > > session.query(MyClass).filter(MyClass.my_prop == value)... > session.query(MyClass).filter_by(my_prop_name=value)... > > I've tried using composite properties for that (passing the factory > function instead of a composite class), and it actually works, but I'm > a little nervous about it: can I have some bad side effect provided > that in *some* cases (but not always) the target object is loaded from > the database. > > I also dislike the fact I have to provide a __composite_values__ on > all the possible target classes, while in my case, I would prefer to > put that logic on the property side. I'd prefer if I could provide a > callable which'd take an instance and output the tuple of values, > instead of the method. Would that be considered a valid use case for > composite properties or am I abusing the system? > > I've also tried to simply change those properties to descriptors so > that I can override __eq__ on the object returned by accessing the > property on the class. This worked fine for "filter". But I also want > to be able to use filter_by. So, I'd wish that > query(Class).filter_by(name=value) would be somehow equal to > query(Class).filter(Class.name == value), but it's not. filter_by only > accepts MapperProperties and not my custom property. > > So what do people think? > > -- > Gaëtan de Mentenhttp://openhex.org --~--~---------~--~----~------------~-------~--~----~ 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 [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---
