流利的抽象类的多层次继承

Question

I'm using VS2010, NHibernate 3.1.0.4000 and fluent Nhibernate 1.2.0.712.

My program contains the following class hierarchy:

public abstract class Stop
{  
}

public abstract class WorkStop : Stop
{
}

public class PatientStop : WorkStop
{
}

public class DoctorStop : WorkStop
{
}

public class HubStop : Stop
{
}

My mappping override is as follows:

 public class StopMappingOverride : IAutoMappingOverride<Stop>
{
    public void Override(AutoMapping<Stop> mapping)
    {
        mapping.DiscriminateSubClassesOnColumn("StopType");
        mapping.SubClass<HubStop>("HubStop");
        mapping.SubClass<WorkStop>("WorkStop").Abstract();
        mapping.References(x => x.Planning).Cascade.None();
    }
}

public class WorkStopMappingOverride : IAutoMappingOverride<WorkStop>
{
    public void Override(AutoMapping<WorkStop> mapping)
    {
        //mapping.Table("Stop");
        mapping.DiscriminateSubClassesOnColumn("StopType");
        mapping.SubClass<DoctorStop>("DoctorStop");
        mapping.SubClass<PatientStop>("PatientStop");
        mapping.HasMany(d => d.Tasks).KeyColumn("StopId")
            .AsSet()
            .Access.CamelCaseField(Prefix.Underscore);

        mapping.References(x => x.Doctor).Cascade.None();
    }
}

public class DoctorStopMappingOverride : IAutoMappingOverride<DoctorStop>
{
    public void Override(AutoMapping<DoctorStop> mapping)
    {
        mapping.References(x => x.Practice).Cascade.None();
        mapping.HasMany(d => d.Protocols).KeyColumn("StopId")
            .AsSet()
            .Access.CamelCaseField(Prefix.Underscore);
        mapping.HasMany(d => d.Materials).KeyColumn("StopId")
            .AsSet()
            .Access.CamelCaseField(Prefix.Underscore);
    }
}
public class PatientStopMappingOverride : IAutoMappingOverride<PatientStop>
{
    public void Override(AutoMapping<PatientStop> mapping)
    {
        mapping.References(x => x.Patient).Cascade.None();
    }
}

public class HubStopMappingOverride : IAutoMappingOverride<HubStop>
{
    public void Override(AutoMapping<HubStop> mapping)
    {
    }
}

The above used to work in previous projects. except for the extra level of abstraction which is workstop, thats new. But then hubstop should still work as i'll illustrate below.

When is use the mapping override as is, i get the error: System.Data.SqlClient.SqlException : Invalid object name 'WORKSTOP'

So i thought, what if i specify the table name, and yes because of the mapping override on WorkStop the discriminator is filled in correctly and doctor and patientstops can be persisted.

But then i get the error: System.Data.SqlClient.SqlException : Invalid object name 'HUBSTOP'

So again i used the table name, but now i get the following error: Cannot insert the value NULL into column 'StopType'

Why doesn't the table discriminator work in the first place, on the stop mapping override?

Answer 1

Try to override

public class AutomappingConfiguration : DefaultAutomappingConfiguration
{
    public override bool IsDiscriminated(System.Type type)
    {
        var types = new System.Type[] { typeof(Stop), typeof(WorkStop) };
        return base.IsDiscriminated(type) || types.Contains(type);
    }