nhibernate (or hibernate) Conditional cascading

I have a class User, that has a property Event, which has many Sessions. Basically, a user register to an event which have many sessions h开发者_如何学Goours.

The user can register for an event, but the sessions hours are purely informative.

But when I write a user to the database with NH, it updates the sessions hours too. How can I prevent that, knowing that I still need the sessions hours to be inserted/updated when I create/update an event.

This might not totally apply to your question, but I've had issues where I wanted to conditionally cascade deletes based on certain business rules.

A lot of the times, you can handle this in your persistence logic. I had a case where I went with NHibernate Event Listeners.

public class ConditionalDeleter: IPostDeleteEventListener
    {
        public void OnPostDelete(PostDeleteEvent @event)
        {
            var foo = @event.Entity as Foo;
            if (foo != null)
            {
                if (foo.ShouldDeleteBar)
                {
                    ISession session = @event.Session.GetSession(EntityMode.Poco);
                    session.Delete(foo.Bar);

                    session.Flush(); 
                }
            }
        }
    }