Question

Ok so I ‘m just getting into nhibernate (using fluent).

One thing that I love about it is that I can use the Repository pattern (read about it from the nhibernate rhino blog).

Basically using generics, I can create methods that will work accross ALL my database tables.

 public interface IRepository<T>
    {
        T GetById(int id);
        ICollection<T> FindAll();
        void Add(T entity);
        void Remove(T entity);
    }


 public class Repository<T> : IRepository<T>
    {

        public ISession Session
        {
            get 
            { 
                return SessionProvider.GetSession(); 
            }
        }


        public T GetById(int id)
        {
            return Session.Get<T>(id);
        }

        public ICollection<T> FindAll()
        {
            return Session.CreateCriteria(typeof(T)).List<T>();
        }

        public void Add(T t)
        {
            Session.Save(t);
        }

        public void Remove(T t)
        {
            Session.Delete(t);
        }    

    }

I then inherit the Repository class and I can then add methods that are specific to that entity.

When trying to add an Update method, someone mentioned that the Repository pattern is suppose to act on collections? Am I looking at things incorrectly here? Why can’t I create an update method?

I tried adding a update method, but I’m confused as to how I will handle the session and update the database?

I want a single place for all my database access for each entity, so UserRepository will have all basic CRUD and then maybe some other methods like GetUserByEmail() etc.

Answer 1

Don’t use the repository pattern – use the UnitOfWork pattern instead, and pass defined query ICriteria to the ISession. Essentially the Repo pattern is wrapping something that doesn’t need to be wrapped with NH.

see http://ayende.com/Blog/archive/2009/04/17/repository-is-the-new-singleton.aspx for more info