NHibernate - access the ID of an associated object without lazy loading the whole object

Question

I have two associated business objects - A and B. the association is (A->B)many-to-one, with B.Id a foreign key in A (so A has A.B_id in the DB).

I\'m using lazy=tru

Answer 1

If you are using NHibernate 3.2 or later, you could use the following code to get the id of associated object without another roundtrip to database to load the whole object:

using NHibernate.Proxy;
...
object id = null;
if (obj.IsProxy()) // obj is the object you want to get its identifier.
{
    var proxy = obj as INHibernateProxy;
    if (proxy != null)
    {
        var li = proxy.HibernateLazyInitializer;
        if (li != null) 
            id = li.Identifier;
    }
}