NHibernate.AssertionFailure: null identifier

Question

Before I kick my computer in to next week...

I've checked out every other question about this, but none of them have the solution. I've stripped this code right back, but it's still not working.

I'm getting this error when saving an object: NHibernate.AssertionFailure: null identifier

This is my mapping file:

public class OrderMap : BaseMap<Order>
{
    public SalesOrderMap()
    {
        Id(x => x.Id).Column("OrderId");
    }
}

This is the entity:

public class Order
{
    public virtual int Id { get; protected set; }
}

This is my test code:

Order order = new Order();
ISession session = SessionFactory.GetCurrentSession();
session.SaveOrUpdate(order); <----EXCEPTION ON THIS LINE
session.Flush();

And then bang...it breaks with

[AssertionFailure: null identifier]
  NHibernate.Engine.EntityKey..ctor(Object identifier, String rootEntityName, String entityName, IType identifierType, Boolean batchLoadable, ISessionFactoryImplementor factory, EntityMode entityMode) +135
   NHibernate.Engine.EntityKey..ctor(Object id, IEntityPersister persister, EntityMode entityMode) +70
   NHibernate.Event.Default.AbstractSaveEventListener.PerformSaveOrReplicate(Object entity, EntityKey key, IEntityPersister persister, Boolean useIdentityColumn, Object anything, IEventSource source, Boolean requiresImmediateIdAccess) +545
   NHibernate.Event.Default.AbstractSaveEventListener.PerformSave(Object entity, Object id, IEntityPersister persister, Boolean useIdentityColumn, Object anything, IEventSource source, Boolean requiresImmediateIdAccess) +322
   NHibernate.Event.Default.AbstractSaveEventListener.SaveWithGeneratedId(Object entity, String entityName, Object anything, IEventSource source, Boolean requiresImmediateIdAccess) +130
   NHibernate.Event.Default.DefaultSaveOrUpdateEventListener.SaveWithGeneratedOrRequestedId(SaveOrUpdateEvent event) +27
   NHibernate.Event.Default.DefaultSaveOrUpdateEventListener.EntityIsTransient(SaveOrUpdateEvent event) +63
   NHibernate.Event.Default.DefaultSaveOrUpdateEventListener.PerformSaveOrUpdate(SaveOrUpdateEvent event) +89
   NHibernate.Event.Default.DefaultSaveOrUpdateEventListener.OnSaveOrUpdate(SaveOrUpdateEvent event) +188
   NHibernate.Impl.SessionImpl.FireSaveOrUpdate(SaveOrUpdateEvent event) +259
   NHibernate.Impl.SessionImpl.SaveOrUpdate(Object obj) +256

if anyone's interested, this is how the session factory is built:

ControllerSource.SessionFactory = Fluently.Configure()
                .Database(MsSqlConfiguration.MsSql2008.ConnectionString(DataConfig.ConnectionString))
                .Mappings(x => x.FluentMappings.Add(typeof (OrderMap)))
                .ExposeConfiguration(c =>{
                                             c.SetProperty("generate_statistics", "false");
                                             c.SetProperty("current_session_context_class", contextClass);
                                             c.SetProperty("cache.use_second_level_cache", "false");
                                             c.SetProperty("cache.use_query_cache", "false");
                                             c.SetProperty("connection.release_mode", "on_close");
                })
                .BuildSessionFactory();

Answer 1

The default generator is Native which will in turn use Identity for SQL Server 2008. My bet is that you don't have identity specified on the column in the table definition.