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 Menten http://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 -~----------~----~----~----~------~----~------~--~---
