Question

With uni-directional mapping and Cascade.All on a collection, is it possible to save only a child, by setting a valid FK then do a Save or SaveOrUpdate ?

If I create a new order, setting a valid Account_id and do a SaveOrUpdate, the Account_id is set to NULL in the database, while the entity still have the Account_id previously set.

Why? and can I modify perhaps the SaveOrUpdate method to make this work?

public class Account
{
    public int Id { get; set; }
    public string Name { get; set; }
    public IList<Order> Orders { get; set; }
    //...
}

public class Order
{
   public int Id { get; set; }
   public int Account__id { get; set; }
   public decimal Price { get; set; }
   //...
}

Mappings:

public  class AccountMap : ClassMap<Account>
{
   public AccountMap()
       : base()
   {
       Id(x => x.Id).GeneratedBy.Identity();
       Map(x => x.Name);
       HasMany(x => x.Orders).KeyColumn("Account__id").Cascade.All(); 
   }
}

Repository:

    public void SaveOrUpdate(T instance)
    {
        using (ISession session = FnhManager.OpenSession())
        {
            using (ITransaction transaction = session.BeginTransaction())
            {
                lock (instance)
                {
                    session.SaveOrUpdate(instance);
                    transaction.Commit();
                }
            }
        }
    }

Answer 1

It looks like you didn’t map Account__id column in Order mappings class. Try to put

Map(x => x.Account_id)

to your OrderMap class.