Custom entity creation (construction) in NHibernate

Question

I have Order class and SubOrder: Order descendant. Now, Order has .Item and SubOrder (obviously) has it, too, but SubOrder needs SubItem to be there. Which is easy when created:

Item = new SubItem((ISomeInterface)this);

but how do I tell NHibernate to create SubItem instead of Item when it loads SubOrder from database (Session.Get<SubOrder>(id))? The type of the item is not in the database (and I don't need and don't want it to be there); it's always "Item for Order, SubItem for SubOrder". Moreover, it needs to be created with (ISomeInterface)SubOrder as constructor parameter.

In short, how do I manage custom entity create in NHibernate to achieve things described above? Is it possible to have a reference to SubOrder when creating SubItem (I can live with property "injection" if not)?

I can probably use IUserType but it seems to be an overkill; and I don't see how to apply IUserType to SubOrder.Item only (same for IInterceptor). Also I don't see how to get a reference to the parent order, except to use OnLoad event for the SubOrder and set SubItem properties there... which is awkward.

Answer 1

"OnLoad event for the SubOrder and set SubItem properties there" -> there's one solution.

Otherwise you could try writing a custom ReflectionOptimizer.