Question

I am trying to map a POCO as a many-to-many relationship. I do not want a property on Behavior that Contains BehavioralEvents. I’m pretty sure the Many-to-Many mapping has to be in both places, however I don’t want the corresponding property on my Behavior class.

I have heard you can use a no-op access operator but im not sure how to do it in Fluent Nhibernate.

Please advise:

public class BehavioralEvent : AggregateRoot    
    {       
        protected internal IList<Behavior> Behaviors { get; private set; }

        public BehavioralEvent()
        {
            Behaviors = new List<Behavior>();
        }
    }

Behavior Class (No reference back to BehavioralEvent)

public class Behavior : AggregateRoot
{
        protected internal virtual string Name { get; private set; }
        protected internal virtual string Definition { get; private set; }           

        public Behavior(string name, Guid id) 
        {
            this.Id = id;
            this.Name = name;               
        }

        protected Behavior(){}          
    }

BehavioralEventClassMap:

public class BehavioralEventClassMap : ClassMap<BehavioralEvent>
    {
        public BehavioralEventClassMap()
        {
            Id(x => x.Id, "BehavioralEventId").GeneratedBy.Assigned();

            HasManyToMany(x => x.Behaviors)
                .Cascade.All()
                .Table("BehaviorData")
                .ParentKeyColumn("BehavioralEventId")
                .ChildKeyColumn("BehaviorId");
        }
    }

BehaviorClassMap:

public class BehaviorClassMap : ClassMap<Behavior>
{
    public BehaviorClassMap()
    {
        Table("Behaviors");
        Id(x => x.Id, "BehaviorId").GeneratedBy.Assigned();
        Map(x => x.Name).Not.Nullable();
        Map(x => x.Definition); 
    }
}

Answer 1

You do not need to map it from both sides.

I have various mappings like this:

HasManyToMany(x => x.SomeCollection).Table("MappingTable").ParentKeyColumn("ParentKey").ChildKeyColumn("ChildKey").Cascade.AllDeleteOrphan();

Works like a charm! Map it as Collection or Set (see http://www.codinginstinct.com/2010/03/nhibernate-tip-use-set-for-many-to-many.html).