Question

I have a common superclass (suppose it’s Employee), which has (amongst others) subclasses Engineer and Salesman.
The table structure of the Employee classes are modelled using table-per-hierarchy.

A Department object references both salesmen and engineers:

public class Department
    {
        public IEnumerable<Engineer> Engineers { get; set; }
        public IEnumerable<Salesman> Salesmen { get; set; }
    }

The problem occurs when I empty the Engineers collection from the Department:

• When both relationships are mapped with cascade=none or cascade=all (on the Department side), then all the Salesman records get their foreign-key set to null (here is the statement generated by nHib: UPDATE dbo.Employee SET Department_id = Null WHERE Department_id = @p0;.
• When both relationships are mapped with cascade=all-delete-orphan then I get an ObjectDeletedException referring to a completly different collection of the Department object (can’t figure this one out)
• when mapped with cascade=all or cascade=none and table per subclass strategy, all seems to be working fine
• when mapped with cascade=all-delete-orphan and table per subclass strategy, I once again get the ObjectDeletedException referring to a completly different collection of the Department object

obviously I’m missing some nHib basic here.. but what is it?

Answer 1

duhh…. inverse=true on the parent class for those collections.
still not sure what caused that seemingly-unrelated ObjectDeletedException though…