Need a simple example of using nhibernate + unit of work + repository pattern + service layer + ninject

Question

I am using

• nhibernate + fluent nhibernate
• asp.net mvc 3
• ninject

Currently I am using nhibernate, ninject with the repository pattern and service layers.

So I have this

ninject

 public class NhibernateSessionFactory
    {
        public ISessionFactory GetSessionFactory()
        {
           ISessionFactory fluentConfiguration = Fluently.Configure()
                                                  .Database(MsSqlConfiguration.MsSql2008.ConnectionString(c => c.FromConnectionStringWithKey("ConnectionString")))
                                                  .Mappings(m => m.FluentMappings.AddFromAssemblyOf<Framework.Data.Mapping.TableAMap>().Conventions.Add(ForeignKey.EndsWith("Id")))
                                                  .ExposeConfiguration(cfg => cfg.SetProperty("adonet.batch_size", "20"))
                                                  .ExposeConfiguration(c => c.SetProperty("generate_statistics", "true"))
                                                  //.ExposeConfiguration(BuidSchema)
                                                  .BuildSessionFactory();

            return fluentConfiguration;
        }

        private static void BuidSchema(NHibernate.Cfg.Configuration config)
        {
            new NHibernate.Tool.hbm2ddl.SchemaExport(config).Create(false, true);
        }


 public class NhibernateSessionFactoryProvider : Provider<ISessionFactory>
    {   
        protected override ISessionFactory CreateInstance(IContext context)
        {
            var sessionFactory = new NhibernateSessionFactory();
            return sessionFactory.GetSessionFactory();
        }
    }


   public class NhibernateModule : NinjectModule
    {
        public override void Load()
        {
            Bind<ISessionFactory>().ToProvider<NhibernateSessionFactoryProvider>().InSingletonScope();
            Bind<ISession>().ToMethod(context => context.Kernel.Get<ISessionFactory>().OpenSession()).InRequestScope()
                                                                                      .OnActivation(StartTransaction)
                                                                                      .OnDeactivation(CommitTransaction);
        }

        public void CommitTransaction(ISession session)
        {

            if (session.Transaction.IsActive)
            {
                session.Transaction.Commit();
            }

        }

        public void StartTransaction(ISession session)
        {
            if (!session.Transaction.IsActive)
            {
                session.BeginTransaction();
            }
        }
    }

So I make my nhibernate session factory once for the lifetime of the application then I use it give me sessions when I need it.

One Start of transaction I start a transaction and at the end I close the transaction.

The reason why I did this was because when I was using the nhibernate profiler I would get alot of warnings about using implicit transactions This sort of put a bandaid on the problem but never really fixed it(it cut down the number but anything lazy loaded still got this problem).

an example repo

 public class CalendarRepo : ICalendarRepo
    {
        private readonly ISession session;

        public CalendarRepo(ISession session)
        {
            this.session = session;
        }

        public List<CalendarAppointment> RepeatingAppointments(int repeatingId)
        {

            List<CalendarAppointment> calendarAppointments = session.Query<CalendarAppointment>().Where(x => x.RepeatingId == repeatingId && x.RepeatingId != 0)
                                                                                                 .Take(QueryLimits.Appointments)
                                                                                                  .ToList();
            return calendarAppointments;

        }
    }

service layer

 public class CalendarService : ICalendarService
    {
        private readonly ICalendarRepo calendarRepo;


        public CalendarService(ICalendarRepo calendarRepo)
        {
            this.calendarRepo = calendarRepo;


        }
        // normally would return something and take in params
         public void SampleServiceMethod()
        {
            // do some checks if needed
            // call up the repository
            // call commit 
            // done.
        }
    }

So that is basically what I have.

I would like to use the unit of work pattern so I get more things commiting and do things properly with the transactions(as right now I been told that I am doing them not quite right)

So I am looking for a simple example on how to get them all to work together and find out how much I need to change of what I got so far.

Most of the tutorials I seen are more complex then I would like. Most do TDD and make generic repositories what is good but before I get to that stage I would like to see a tutorial that does thing simply even if it is repeating code.

Edit

---

So I been playing around with it and came up with this very very simple example. I am not sure if I am doing it right.

Ninject

/// <summary>
/// Load your modules or register your services here!
/// </summary>
/// <param name="kernel">The kernel.</param>
private static void RegisterServices(IKernel kernel)
{

   kernel.Bind<ISessionFactory>().ToProvider<NhibernateSessionFactoryProvider>().InSingletonScope();
   kernel.Bind<ISession>().ToMethod(context => context.Kernel.Get<ISessionFactory>().OpenSession()).InRequestScope();
   kernel.Bind<ITable1Repo>().To<Table1Repo>();
   kernel.Bind<ITable1Service>().To<Table1Service>();
   kernel.Bind<IUnitofWork>().To<UnitofWork>();

}  

The nhibernate factory class is shown in orginal post.

 // Controller
  public class Default1Controller : Controller
    {
        private readonly ITable1Service table1Service;
        //
        // GET: /Default1/
        public Default1Controller(ITable1Service table1Service)
        {
            this.table1Service = table1Service;
        }

        public ActionResult Index()
        {
            table1Service.Save();
            return View();
        }

    }

// domain

  public class Table1
    {
        public virtual int Id { get; private set; }
        public virtual string C1 { get;  set; }
        public virtual string C2 { get; set; }
    }

// Fluent Mapping

  public class Table1Mapping : ClassMap<Table1>
    {
        public Table1Mapping()
        {
            Id(x => x.Id);
            Map(x => x.C1);
            Map(x => x.C2);
        }
    }

//Repo

 public class Table1Repo : unitofwork.Models.Repository.ITable1Repo
    {
        private readonly ISession session;

        public Table1Repo(ISession session)
        {
            this.session = session;
        }

        public void Create(Table1 tbl1)
        {
            session.Save(tbl1);
        }
    }

// service layer

 public class Table1Service : unitofwork.Models.Service.ITable1Service
    {
        private readonly ITable1Repo table1Repo;
        private readonly IUnitofWork unitOfWork;
        public Table1Service(ITable1Repo table1Repo, IUnitofWork unitOfWork)
        {
            this.table1Repo = table1Repo;
            this.unitOfWork = unitOfWork;
        }

        public void Save()
        {
            Table1 a = new Table1();
            a.C1 = "test";
            a.C2 = "test2";

            table1Repo.Create(a);
            unitOfWork.Commit();


        }
    }

// Unit of work

public class UnitofWork : unitofwork.Models.IUnitofWork
    {
        private readonly ITransaction transaction;
        private readonly ISession session;

        public UnitofWork(ISession session)
        {
            this.session = session;
            session.FlushMode = FlushMode.Auto;
            transaction = session.BeginTransaction(IsolationLevel.ReadCommitted);
        }

        public void Commit()
        {
            if (!transaction.IsActive)
            {
                throw new InvalidOperationException("Oops! We don't have an active transaction");
            }
            transaction.Commit();
        }

        public void Rollback()
        {
            if (transaction.IsActive)
            {
                transaction.Rollback();
            }
        }

        public void Dispose()
        {
            if (session.IsOpen)
            {
                session.Close();
            }
        }
    }

Keelboat

You need a new session for each unit of work. – Severance

Answer 1

I'm using 'vanilla' ASP.NET, rather than ASP.NET MVC 3, but essentially we are doing the same things.

First off, I have a seperate UnitOfWork class like this:

public class UnitOfWork
{
    private static ISessionFactory SessionFactory
    {
        get
        {
            return Container.Get<ISessionFactory>();
        }
    }

    public static ISession Session
    {
        get
        {
            return SessionFactory.GetCurrentSession();
        }
    }

    public static void Start()
    {
        CurrentSessionContext.Bind(SessionFactory.OpenSession());
        Session.FlushMode = FlushMode.Commit;
        Session.BeginTransaction(IsolationLevel.ReadCommitted);
    }

    public static void Rollback()
    {
        Rollback(true);
    }

    /// <summary>
    /// Rollback the current transaction, and optionally start a new transaction
    /// </summary>
    /// <param name="startNew">Whether to start a new transaction and keep the session open</param>
    public static void Rollback(bool startNew)
    {
        ISession session = CurrentSessionContext.Unbind(SessionFactory);

        if (session != null)
        {
            // Rollback current transaction
            if (session.Transaction.IsActive && !session.Transaction.WasRolledBack)
            {
                session.Transaction.Rollback();
            }

            // Close and discard the current session
            session.Close();
            session.Dispose();
            session = null;
        }

        if (startNew)
        {
            Start();
        }
    }

    /// <summary>
    /// Commit the current transaction, keeping the current session open and starting a new transaction
    /// 
    /// Call Commit multiple times during a single unit of work if you want to commit database changes in
    /// multiple transactions
    /// </summary>
    public static void Commit()
    {
        Commit(true);
    }

    /// <summary>
    /// Commit the current transaction, and optionally keep the session open and start a new transaction
    /// 
    /// Call Commit multiple times during a single unit of work if you want to commit database changes in 
    /// multiple transactions
    /// </summary>
    /// <param name="startNew">Whether to start a new transaction and keep the session open</param>
    public static void Commit(bool startNew)
    {
        if (startNew)
        {
            Session.Transaction.Commit();
            Session.BeginTransaction(IsolationLevel.ReadCommitted);
        }
        else
        {
            ISession session = CurrentSessionContext.Unbind(SessionFactory);

            if (session != null)
            {
                if (session.Transaction.IsActive && !session.Transaction.WasRolledBack)
                {
                    session.Transaction.Commit();
                }

                session.Close();
                session.Dispose();
                session = null;
            }
        }
    }
}

I use an HTTP module to start a new unit of work for every web request, and to automatically commit/rollback. Not sure if you need an HTTP module when using ASP.NET MVC 3, or if there is some other way of doing it. Anyway, relevant parts shown below:

public class IoCHttpModule : IHttpModule, IDisposable
{
private HttpApplication httpApplication;

public void Init(HttpApplication context)
{
    if (context == null)
        throw new ArgumentException("context");

    this.httpApplication = context;

    this.httpApplication.BeginRequest += new EventHandler(BeginRequest);
    this.httpApplication.EndRequest += new EventHandler(EndRequest);
    this.httpApplication.Error += new EventHandler(Error);

    StandardIoCSetup.Initialise(SessionContextType.Web);
}

private void BeginRequest(object sender, EventArgs e)
{
    UnitOfWork.Start();
}

private void EndRequest(object sender, EventArgs e)
{
    UnitOfWork.Commit(false);
}

private void Error(object sender, EventArgs e)
{
    UnitOfWork.Rollback(false);
}

public void Dispose()
{
    if (this.httpApplication == null)
        return;

    this.httpApplication.Dispose();
}
}

So a new unit of work is started for every web request, and automatically committed if there are no unhandled exceptions. Of course, you can manually call UnitOfWork.Commit() or UnitOfWork.Rollback() within a web request, if required. The line StandardIoCSetup.Initialise... configures NHibernate using a Ninject module, much the same as you are already doing.

So in essence, it's not much work to add a unit of work to what you already have.

Headwaters

I know this is an old post, but I'm curious - isn't the static Session method a potential problem for overlapping requests? – Barra

@MikeKantor This isn't a problem, as we let NHibernate manage session context - the Session getter might be static, but what it returns depends on the session context we have configured. In this case we are using the 'web' session context, which uses a single session per request (I believe by storing it in HttpContext.Current.Items). Looking back, having everything static on UnitOfWork class does seem a bit ugly. I'd probably only use instance props/methods and inject a UnitOfWork instance into classes that needed it. – Headwaters