Question

I have been putting off this question for some time but now it is bothering me all the time. I have 2 classes (These classes are automapped – I leave out public and virtual for brevity.):

class Cashier
{
    int Id {get; set;}
    string name{get; set;}
    IList<Site> Sites {get; set;}
}

class Site
{
    int Id{get; set;}
    string name {get; set;}
    Cashier Cashier {get; set;}
}

I load cashiers with this :

sealed class Repository<T> : IRepository<T> where T :class
    {
        public IList<T> Items { get; private set; }

        public void Load()
        {
            Items.Clear();
            var session = SessionHelper.GetSession();
            session.Clear();
            using (var tx = session.BeginTransaction())
            {
                var list = session.Query<T>().ToList();

                foreach (var obj in list)
                {
                    Items.Add((T)session.Merge(obj));
                }

                session.Clear();
                tx.Commit();
            }
        }
//more
}

and in a winform i bind it to a bindingsource like this:

cashierBindingSource.DataSource = Cashiers;

I set this bindingsource as the data source of a combobox and when I run the application and click on the combobox this exception is thrown at me :

Initializing[HRProject.Model.Cashier#1]-failed to lazily initialize a collection of role: HRProject.Model.Cashier.Sites, no session or session was closed

I found that providing a mapping override fixes this problem

mapping.HasMany(x => x.Sites).Not.LazyLoad().Cascade.All();

However, I have many such classes and I get the feeling there’s a cleaner way to get this done. Any ideas?

Answer 1

In my experience, FNH, WinForms data binding, and lazy loading are a difficult mix.

If you need lazy loading, you need to keep a session open for the life of the form.

If you don’t need it, you can turn it off.

The easiest way I’ve found to do this for a whole project is to use the DefaultLazy convention:

.Conventions.Add( DefaultLazy.Never() )

Go to “The Simplest Conventions” section on the wiki, for this, and a list of others.

Here’s the list from the Wiki:

Table.Is(x => x.EntityType.Name + "Table")
PrimaryKey.Name.Is(x => "ID")
AutoImport.Never()
DefaultAccess.Field()
DefaultCascade.All()
DefaultLazy.Always()
DynamicInsert.AlwaysTrue()
DynamicUpdate.AlwaysTrue()
OptimisticLock.Is(x => x.Dirty())
Cache.Is(x => x.AsReadOnly())
ForeignKey.EndsWith("ID")

A word of warning – some of the method names in the Wiki may be wrong. I edited the Wiki with what I could verify (i.e. DefaultCascade and DefaultLazy), but can’t vouch for the rest. But you should be able to figure out the proper names with Intellisense if the need arises.