On Dec 17, 2008, at 2:28 AM, Joril wrote:
> > Michael Bayer ha scritto: > >> "concrete inheritance", as referenced in that post, was not designed >> to be used as a configurational spacesaver and always requires a >> mapped selectable for the "base", which you don't have here, so it's >> not appropriate for this use case. >> >> >> So for this you'd need a custom metaclass: > > I see, thanks! Now my problem is that I already have a custom > metaclass, defining a set of common attributes for ALL my classes.. > So, to declare additional fields for just a few classes, would it be > ok to subclass the custom metaclass again and re-call declarative_base > ()? > > To clarify: > All classes have a "timestamp" attribute, and a few of them has a > "notes" attribute too. > > Thanks again! yes that is entirely OK. A second "declarative_base" may share the metadata of the first, Base = declarative_base(metadata=somemetadata). If you want to use strings for relation() classes across the two bases, the _decl_class_registry would need to be shared as well: meta = MetaData() Base1 = declarative_base(metadata=meta, metaclass=MyMetaClass) Base2 = declarative_base(metadata=meta, metaclass=MyOtherMetaClass) Base2._decl_class_registry = Base1._decl_class_registry This is a use case we can make easier in a future release. --~--~---------~--~----~------------~-------~--~----~ 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 sqlalchemy+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---
