Fluent NHibernate cascade delete not working

Question

I've got a simple phone directory app using Fluent NHibernate 1.1. In the app, a "Person" object has many "PhoneNumber" objects. I'm trying to delete a Person and I want to cascade deletes to PhoneNumbers. I set a convention of DefaultCascade.All() after reading this answer. However, attempting to delete the parent object still throws an exception--it appears that NHibernate is trying to update the child table to set the parent ID to null instead of just deleting the record:

{"could not delete collection: [Person.PhoneNumbers#473][SQL: UPDATE phone_numbers SET person_id = null WHERE person_id = @p0]"}

InnerException:

{"Cannot insert the value NULL into column 'person_id', table 'directory.dbo.phone_numbers'; column does not allow nulls. UPDATE fails.\r\nThe statement has been terminated."}

My Fluent config is:

public static ISessionFactory CreateSessionFactory() {
    return Fluently.Configure()
        .Database(MsSqlConfiguration.MsSql2008
            .ConnectionString(ConfigurationManager.ConnectionStrings[ConfigurationManager.AppSettings["activeConnStr"]].ConnectionString))
        .Mappings(m => m.FluentMappings.AddFromAssemblyOf<Person>()
                                        .Conventions.Add(DefaultCascade.All())
                    )
        .BuildSessionFactory();
}

The parent class is:

public class Person {
    public Person() {
        PhoneNumbers = new List<PhoneNumber>();
        EmailAddresses = new List<string>();
    }

    public virtual int Id { get; private set; }
    public virtual string FirstName { get; set; }
    public virtual string LastName { get; set; }
    public virtual string Company { get; set; }
    public virtual IList<PhoneNumber> PhoneNumbers { get; set; }
    public virtual IList<string> EmailAddresses { get; set; }
}

The child class (PhoneNumber) is:

public class PhoneNumber {
    public virtual string Number { get; set; }
    public virtual PhoneNumberType NumberType { get; set; }
    public virtual Person Person { get; set; }
}

My code to delete a person is:

public static void DeletePerson(int id) {
    using (var session = Dalc.Instance.SessionFactory.OpenSession()) {
        using (var trans = session.BeginTransaction()) {
            session.Delete(session.Load<Person>(id));
            trans.Commit();
        }
    }
}

What am I doing wrong?

Answer 1

I'm not sure about configuring the Fluent part, but I recently had the same problem with ActiveRecord.

You need to set your association, on the Person side, as "Inverse = true".

From looking at this page: http://wiki.fluentnhibernate.org/Getting_started

I belive, you need to set this when defining your HasMany relationship in Person. It should look something like this:

public PersonMap()
{
    //<...SNIP...>
    HasMany(x => x.PhoneNumbers)
      .Inverse();
    //<...SNIP...>
}