Yet another way to manage your NHibernate ISessionFactory

So here is my current UnitOfWork implementation.  This one makes use of the somewhat new current_session_context_class feature. I think this is quite simple compared to some of the others you will find.

public interface IUnitOfWork : IDisposable
    {
        IUnitOfWork Start();
        void BeginTransaction();
        void CommitTransaction();
        void RollbackTransaction();
    }

public class UnitOfWork : IUnitOfWork
    {
        #region Dependencies

        public ISessionFactory SessionFactory
        {
            get;
            set;
        }

        #endregion

        #region IUnitOfWork Members

        public virtual void BeginTransaction()
        {
            var session = SessionFactory.GetCurrentSession();
            if ( !session.Transaction.IsActive )
            {
                session.BeginTransaction();
            }
        }

        public virtual void CommitTransaction()
        {
            var session = SessionFactory.GetCurrentSession();
            if ( session.Transaction.IsActive )
            {
                session.Transaction.Commit();
            }
        }

        public void RollbackTransaction()
        {
            var session = SessionFactory.GetCurrentSession();
            if ( session.Transaction.IsActive )
            {
                session.Transaction.Rollback();
            }
        }

        public IUnitOfWork Start()
        {
            if ( !CurrentSessionContext.HasBind(SessionFactory) )
            {
                var session = SessionFactory.OpenSession();
                session.FlushMode = FlushMode.Commit;
                CurrentSessionContext.Bind(session);
            }
            return this;
        }

        #endregion

        #region IDisposable Members

        public void Dispose()
        {
            var session = CurrentSessionContext.Unbind(SessionFactory);
            var transaction = session.Transaction;
            if ( transaction.IsActive )
            {
                transaction.Dispose();
            }
            session.Dispose();
        }

        #endregion
    }

All that’s required is this in the hibernate config section:

(for web apps):

<property name="current_session_context_class">web</property>

(for pretty much anything else): 

<property name="current_session_context_class">thread_static</property>

and just the barebones bootstrapping:

var sessionFactory = new Configuration().Configure().BuildSessionFactory();
            

Of course, to get this to work you need to register that sessionFactory instance into your IoC container, and register the UnitOfWork type with the container with a transient lifecycle.

From there you can either explicitly create and dispose IUnitOfWork instances for each operation, or set up a HttpModule to create one at the start of each request and dispose of it in the end_request event.