Question

I have a problem with this piece of code
If I don’t use the transaction (I commented here in that code), the update won’t occur.

using (var session = Repository.TSession())
{
  var utilisateurDal = new UtilisateurDal(session);
  var utilisateur = utilisateurDal.GetUtilisateur(login);
  if (utilisateur != null)
  {
    //var transaction = Session.BeginTransaction();
    utilisateur.MotDePasse = "test";
    session.Update(utilisateur);
    //transaction.Commit();
  }
}

The code which retrieve the object to update :
(Please note that login isn’t an unique identifier)

public Utilisateur GetUtilisateur(ISession session, string login)
{
  return session.Query<Utilisateur>().SingleOrDefault(u => u.Identifiant == login);
}

When I enable the debug mode I have that message :

NHibernate.Event.Default.DefaultSaveOrUpdateEventListener: 2011-11-16 14:14:57,832 [35] DEBUG NHibernate.Event.Default.DefaultSaveOrUpdateEventListener [(null)] - ignoring persistent instance
NHibernate.Event.Default.DefaultSaveOrUpdateEventListener: 2011-11-16 14:14:57,833 [35]     DEBUG NHibernate.Event.Default.DefaultSaveOrUpdateEventListener [(null)] - object already associated with session: [BusinessObjets.Utilisateur#3]

Do you the meaning of this behaviour ?

Regards

Answer 1

NHibernate doesnt send the Update-statement immediatly and will cache it. On the next session.Flush() all Updates are sent together to save roundtrips. transaction.Commit() will Flush all changes to the db, otherwise a commit in the db wont know the updates.

you can even omit session.Update(utilisateur); because the session tracks the entities loaded through it and will send all changes to db on the next Flush().

Either use a transaction or call session.Flush(); at the end of your updates.

this could look like this

using (var session = Repository.TSession())
using (var transaction = Session.BeginTransaction())
{
    var utilisateurDal = new UtilisateurDal(session);
    var utilisateur = utilisateurDal.GetUtilisateur(login);
    if (utilisateur != null)
    {
        utilisateur.MotDePasse = "test";
    }
    transaction.Commit();
}