Question

With ASP.net MVC I’m doing this:

[HttpPost]
[TransactionFilter]
public ActionResult Create(User user)
{
    // Ommited some things for the sake of brevity
    _userRepository.Add(user);
    return RedirectToAction("Details", new { Id = user.Id });
}

This works as I expected. Now I’m trying to do this:

[HttpPost]
[TransactionFilter]
public ActionResult Create(User user, ChildOfUser userChild)
{
    // Ommited some things for the sake of brevity
    var parent = _userRepository.GetById(user.Id);
    parent.Children.Add(userChild);

    return RedirectToAction("Details", new { Id = userChild.Id });
}

This fails because userChild.Id is null. The first case works because in the repo I call session.Save(user);, and this call will change the user.Id property.

The (User)parent.Children.Add(userChild); call won’t change the userChild.Id property. Only after calling transaction.Commit(); the userChild.Id will have a meaningfull value. While I expect that the Id would be set by adding the userChild to the collection.

Now, should NHibernate handle this? Or are my expectations wrong? If there’s a way to let NHibernate handle this that would be awesome.

EDIT
The Id’s in this case are always GUID’s. Can I set them myself (they are Globally unique right…), and will NHibernate use that as if it generated the Id itself?

Answer 1

I’ve had this particular problem solved by using the ISession.Flush() method after using .Add()

I wouldn’t recommend this practise though. Nowadays I set the Guid Id immediately in the entities constructor. This makes both MVC and NHibernate happy.