Category Archives: Fluent NHibernate

Updated NHibernate articles

It wouldn’t surprise me if nobody noticed, but I overhauled my NHibernate articles. They are now grouped together in one convenient location.

Maybe when I have time, I will write about all the things I was doing wrong and how I fixed them.

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Fluent NHibernate, auto mappings, ASP.NET MVC 3, Castle Windsor, and NUnit… and Moq

I’m going for a record: internet’s longest blog post title. FNHAMASPDNMVC3CWNUM is the official acronym of this post.

This is the fourth article in a series on using Fluent NHibernate with auto mappings. This time, I will cover unit testing with NUnit and Moq. If you haven’t already, you might want to catch up:

  1. How to use Fluent NHibernate with auto mappings
  2. Fluent NHibernate, auto mappings and ASP.NET MVC 3
  3. Fluent NHibernate, auto mappings, ASP.NET MVC 3, and Castle Windsor

You may be asking yourself, “What is unit testing and why would I want to do it?” If that’s the case, then you should read my previous article: What is unit testing? Dependency injection?

Here’s what the completed project will look like:

If you don’t see the solution at the top of the Solution Explorer, go to the Tools menu > Options. In the Options window, ensure “Show all settings” is checked, then go to Projects and Solutions on the left and check “Always show solution” on the right:

This time, you don’t need to create a new ASP.NET MVC 3 web application. Instead, open the solution from last time, right click on the solution at the top of the Solution Explorer and choose Add > New Project…:

Choose Visual C# Class Library as the project template and name it CastleFluentNHibernateMvc3.Tests. Once the project has been added to the solution, delete the Class1 class. Next, right click on the Tests project in the Solution Explorer and choose Manage NuGet Packages… Search the online gallery for NUnit and install it. Also, search for and install Moq.

Once the packages have been downloaded and installed, add a folder to the Tests project named Controllers, then add a class to the Controllers folder named HomeControllerTest. Make this class public and prepend it with the TestFixture attribute, like so:

[TestFixture]
public class HomeControllerTest { }

Finally, we’re ready to write some tests!

Remember, a unit test typically covers a single unit of code. In the case of a MVC application, that means that each action and method deserves its own unit test. Depending on the complexity, some actions and methods deserve several unit tests. Because our application is so simple, however, our unit tests will be relatively simple as well. As you can tell from the previous step, we will be writing unit tests for the actions in our home controller, starting with the Index action. For convenience, here is the code:

public ActionResult Index()
{
    storeRepository.BeginTransaction();

    var stores = storeRepository.GetAll();

    if ( stores == null || !stores.Any() )
    {
        storeRepository.Rollback();

        return View( "Error" );
    }
    
    try
    {
        storeRepository.Commit();

        return View( stores.ToList() );
    }
    catch
    {
        storeRepository.Rollback();

        return View( "Error" );
    }
}

We want to make sure that every time the Index action is called the store repository returns a list of stores and the action returns a view. Testing that the action returns a view is simple enough, so at first we might try something like this:

[Test]
public void Index()
{
    // Arrange
    var controller = new HomeController();

    // Act
    var result = controller.Index();

    // Assert
    Assert.IsInstanceOf<ViewResult>( result );
}

The first thing you’ll notice is that the Tests project requires a reference to CastleFluentNHibernateMvc3, as well as System.Web.Mvc. Once you’ve added these references, Visual Studio will display this compilation error:

'CastleFluentNHibernateMvc3.Controllers.HomeController' does not contain a constructor that takes 0 arguments

The reason we get this error is because we modified the home controller constructor last time to use dependency injection. We did this because we don’t want to use our real repository in our unit tests. Instead, we want to use a fake (or mock) repository. This is where Moq comes in handy, although it does require a little setup before we can use it. First, we need a field to store our fake repository in the HomeControllerTest class, which we need to reset after each test execution:

[TestFixture]
public class HomeControllerTest
{
    private Mock<IRepository<Store>> storeRepositoryMock;

    [SetUp]
    public void Init()
    {
        storeRepositoryMock = new Mock<IRepository<Store>>();
    }

    // ...
}

Now, we can pass this value to the home controller constructor in our unit test, exposing its mocked instance with Moq’s Object property:

[Test]
public void Index()
{
    // Arrange
    var controller = new HomeController( storeRepositoryMock.Object );

    // Act
    var result = controller.Index();

    // Assert
    Assert.IsInstanceOf<ViewResult>( result );
}

Eventually, we may end up with lots of injected dependencies in our home controller constructor, so I like to extract the constructor call to a separate method:

[Test]
public void Index()
{
    // Arrange
    var controller = GetHomeController();

    // Act
    var result = controller.Index();

    // Assert
    Assert.IsInstanceOf<ViewResult>( result );
}

private HomeController GetHomeController()
{
    return new HomeController( storeRepositoryMock.Object );
}

At this point, if we try running our application, we will get a nasty error. We can’t run a class library directly. There are two options for running NUnit tests:

  1. Download NUnit and run it in the console or run the GUI tool. After compiling the Tests project, load the .dll file (located in the project’s bin/Debug folder) in NUnit and run the test.
  2. Download the Visual NUnit extension for Visual Studio. Go to View > Other Windows > Visual NUnit. After compiling the Tests project, select it in Visual NUnit and run the test.

Whichever option you choose, our test should pass with flying colors! Unfortunately, there’s a problem. We’ve made sure our action returns a view, but the view it’s returning is actually the Error view. We can verify this by debugging our test. In Visual Studio, go to Debug > Attach to process… find nunit-agent.exe (if you chose option one above) or VisualNUnitRunner.exe (if you chose option two) in the list of processes and click the Attach button.

Now, we can put a breakpoint in our test and take a closer look at our result. Sure enough, the ViewName is “Error”:

We could have caught this sooner by testing that the view is getting the right model. In this case, our view should be getting a list of stores as its model. We would test for that as follows:

[Test]
public void Index()
{
    // Arrange
    var controller = GetHomeController();

    // Act
    var result = controller.Index();

    // Assert
    Assert.IsInstanceOf<ViewResult>( result );

    var view = (ViewResult)result;

    Assert.IsInstanceOf<List<Store>>( view.Model );
}

If we run our test again, it should fail. NUnit will display the following error:

CastleFluentNHibernateMvc3.Tests.Controllers.HomeControllerTest.Index:
  Expected: instance of <System.Collections.Generic.List`1[CastleFluentNHibernateMvc3.Models.Store]>
  But was:  null

Let’s put a breakpoint in our home controller this time and find out what’s going on. Doing this, we can see that our store repository is not returning any stores. And why should it? Remember, it’s a fake repository! We have to tell our fake repository what to do when it’s queried for a list of stores. But before we do that, make a copy of the Index test and rename it to Index_NoStoresFound. With a little modification, this test can still be useful:

[Test]
public void Index_NoStoresFound()
{
    // Arrange
    var controller = GetHomeController();

    // Act
    var result = controller.Index();

    // Assert
    Assert.IsInstanceOf<ViewResult>( result );
    
    var view = (ViewResult)result;

    Assert.AreEqual( "Error", view.ViewName );
}

Keeping this test will ensure that the Index action always returns the Error view when our store repository doesn’t return any stores. If this test ever fails (for instance, because the Index action returns the Index view), then something is wrong with our error handling.

Now, let’s fix our Index test. We can use Moq’s Setup method to tell Moq what to return when we ask it for a list of stores:

[Test]
public void Index()
{
    // Arrange
    var controller = GetHomeController();

    var stores = new List<Store>
        {
            new Store()
        };

    storeRepositoryMock.Setup( s => s.GetAll() )
        .Returns( stores.AsQueryable() )
        .Verifiable();

    // Act
    var result = controller.Index();

    // Assert
    storeRepositoryMock.Verify();

    Assert.IsInstanceOf<ViewResult>( result );

    var view = (ViewResult)result;

    Assert.IsInstanceOf<List<Store>>( view.Model );
}

Notice that we can return any list of stores we want, so long as we convert it to an IQueryable because that’s what Moq expects to get back from the GetAll method of our store repository.

That concludes my series on using Fluent NHibernate with auto mappings. As always, let me know if you have any questions or comments. Good luck!

Fluent NHibernate, auto mappings, ASP.NET MVC 3, and Castle Windsor

The title of this article is so long, I briefly considered using an acronym. Unfortunately, FNHAMASPDNMVC3CW doesn’t communicate much except to the nerdiest of nerds.

This is the third article in a series on using Fluent NHibernate with auto mappings. The first one demonstrated its basic functionality in a console application, and the second one showed how to convert the first one into an ASP.NET MVC 3 application. This article will cover how to use Castle Windsor for dependency injection, which is important for unit testing. I won’t include any unit tests in this article, but will lay the foundation that will make unit testing possible for my next article.

Much of the code below is directly from the Castle Windsor documentation, which really is exceptional.

Here’s what the completed project will look like:

Once again, create a new ASP.NET MVC 3 web application in Microsoft Visual Studio 2010 and use the empty project template. This time, call your project CastleFluentNHibernateMvc3. Next, right click on the project in the Solution Explorer and choose Manage NuGet Packages… Search the online gallery for Fluent NHibernate and install it. We also need Castle Windsor, so search for that and install it too.

EDIT 12/18/2012: You can get the source code on GitHub.

Once you’ve installed the packages, copy the Controllers, Models and Repositories folders from our previous project to our new project. Also, copy the Views/Home folder to our new project. Make sure you change the namespace in each file accordingly.

The first thing we need is a Windsor controller factory. The Windsor controller factory overrides two methods of the default MVC controller factory and is central to how Castle Windsor resolves controller dependencies. Create this class in a new Windsor directory at the root level of the project:

namespace CastleFluentNHibernateMvc3.Windsor
{
    public class WindsorControllerFactory : DefaultControllerFactory
    {
        private readonly IKernel kernel;

        public WindsorControllerFactory( IKernel kernel )
        {
            this.kernel = kernel;
        }

        public override void ReleaseController( IController controller )
        {
            kernel.ReleaseComponent( controller );
        }

        protected override IController GetControllerInstance( RequestContext requestContext, Type controllerType )
        {
            if (controllerType == null)
            {
                throw new HttpException( 404, string.Format( "The controller for path '{0}' could not be found.", requestContext.HttpContext.Request.Path ) );
            }

            return (IController)kernel.Resolve( controllerType );
        }
    }
}

Next, we need to tell MVC to use the Windsor controller factory instead of the default one. To do that, we’ll add a couple of methods to the MvcApplication class, which resides in the Global.asax.cs file at the root of the project:

namespace CastleFluentNHibernateMvc3
{
    public class MvcApplication : System.Web.HttpApplication
    {
        private static IWindsorContainer container;

        private static void BootstrapContainer()
        {
            container = new WindsorContainer()
                .Install( FromAssembly.This() );

            var controllerFactory = new WindsorControllerFactory( container.Kernel );

            ControllerBuilder.Current.SetControllerFactory( controllerFactory );
        }

        // RegisterGlobalFilters and RegisterRoutes methods go here...

        protected void Application_Start()
        {
            AreaRegistration.RegisterAllAreas();

            RegisterGlobalFilters( GlobalFilters.Filters );
            RegisterRoutes( RouteTable.Routes );

            BootstrapContainer();
        }

        protected void Application_End()
        {
            container.Dispose();
        }
    }
}

Now, we need to tell Windsor about our controllers, including where they reside and how to configure them. In other words, we’ll “register” our controllers with the Windsor “container.” We do this using an “installer.” Create this class in your Windsor directory:

namespace CastleFluentNHibernateMvc3.Windsor
{
    public class ControllersInstaller : IWindsorInstaller
    {
        public void Install( IWindsorContainer container, IConfigurationStore store )
        {
            container.Register( Classes.FromThisAssembly()
                                .BasedOn<IController>()
                                .LifestyleTransient() );
        }
    }
}

Next, create a new class named PersistenceFacility in your Windsor directory, and move the CreateSessionFactory, CreateDbConfig, CreateMappings and UpdateSchema methods of our NHibernateSessionPerRequest class there:

namespace CastleFluentNHibernateMvc3.Windsor
{
    public class PersistenceFacility : AbstractFacility
    {
        protected override void Init()
        {
            Kernel.Register(
                Component.For<ISessionFactory>()
                    .UsingFactoryMethod( CreateSessionFactory ),
                Component.For<ISession>()
                    .UsingFactoryMethod( OpenSession )
                    .LifestylePerWebRequest() );
        }

        private static ISession OpenSession( IKernel kernel )
        {
            return kernel.Resolve<ISessionFactory>().OpenSession();
        }

        // CreateSessionFactory, CreateDbConfig, CreateMappings and UpdateSchema methods go here...
    }
}

In the Init method, we’re telling Castle Windsor what to do when it encounters a dependency on ISessionFactory or ISession. If we ask for an ISession, it will resolve the dependency using the OpenSession method. Notice that this method needs an ISessionFactory, which Castle Windsor will resolve by calling CreateSessionFactory.

We’re also telling Castle Windsor that an ISession instance should be bound to a web request. Since we aren’t specifying a lifestyle for ISessionFactory, the default value of singleton will be used. In other words, only one session factory will be instantiated during the lifetime of our app, and it will hang around in memory until our app dies. This is basically the same thing we did before with our custom HTTP module, except the dependencies will only be resolved when needed. We can verify this by placing breakpoints in the OpenSession and CreateSessionFactory methods and running the app.

Now, we need to register our persistence facility with the Windsor container. Again, we do this using an installer. Create this class in your Windsor directory:

namespace CastleFluentNHibernateMvc3.Windsor
{
    public class PersistenceInstaller : IWindsorInstaller
    {
        public void Install( IWindsorContainer container, IConfigurationStore store )
        {
            container.AddFacility<PersistenceFacility>();
        }
    }
}

Next, we need to add a few more methods to our repository in order to manage NHibernate transactions: BeginTransaction, Commit and Rollback. Previously, we created a custom HTTP module to take care of these operations at the beginning and end of each web request. This time, we’ll manage each transaction ourselves, gaining more control and performance in the process. The GetAll, Get, SaveOrUpdateAll and SaveOrUpdate methods will stay the same:

namespace CastleFluentNHibernateMvc3.Repositories
{
    public interface IRepository<T>
    {
        void BeginTransaction();
        void Commit();
        void Rollback();
        // GetAll, Get, SaveOrUpdateAll and SaveOrUpdate signatures go here...
    }
}
namespace CastleFluentNHibernateMvc3.Repositories
{
    public class Repository<T> : IRepository<T>
    {
        private readonly ISession session;

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

        public void BeginTransaction()
        {
            session.BeginTransaction();
        }

        public void Commit()
        {
            session.Transaction.Commit();
        }

        public void Rollback()
        {
            session.Transaction.Rollback();
        }

        // GetAll, Get, SaveOrUpdateAll and SaveOrUpdate implementations go here...
    }
}

Notice that the repository constructor has been modified to accept an argument of type ISession. This is called dependency injection, and its benefits will become more clear when we use it in our home controller.

But first, we need to register our repositories with the Windsor container. How do we do that? Right! (You did say “use an installer,” right? Good.) Create this class in your Windsor directory:

namespace CastleFluentNHibernateMvc3.Windsor
{
    public class RepositoriesInstaller : IWindsorInstaller
    {
        public void Install( IWindsorContainer container, IConfigurationStore store )
        {
            container.Register( Classes.FromThisAssembly()
                                .Where( Component.IsInSameNamespaceAs<Repository<Store>>() )
                                .WithService.DefaultInterfaces()
                                .LifestyleTransient() );
        }
    }
}

Now, modify the home controller constructor as follows:

// Constructs our home controller
public HomeController( IRepository<Store> storeRepository )
{
    this.storeRepository = storeRepository;
}

The benefit of using dependency injection here is that we no longer have a dependency on a concrete repository. The home controller doesn’t care what the repository does with our data, as long as it implements IRepository. This way, we can change our repository methods without changing our controller actions. Later, when we write unit tests for our controller actions, we’ll be able to create an instance of the home controller using a fake repository so that our tests don’t touch our data.

Because we are no longer using a custom HTTP module to manage NHibernate transactions, we need to call the BeginTransaction method of our repository whenever we get data from or save data to the database. We also need to call the Commit method to flush the NHibernate session, and call the Rollback method if any errors occur:

// Gets all the stores from our database and returns a view that displays them
public ActionResult Index()
{
    storeRepository.BeginTransaction();

    var stores = storeRepository.GetAll();

    if ( stores == null || !stores.Any() )
    {
        storeRepository.Rollback();

        return View( "Error" );
    }
    
    try
    {
        storeRepository.Commit();

        return View( stores.ToList() );
    }
    catch
    {
        storeRepository.Rollback();

        return View( "Error" );
    }
}

// Gets and modifies a single store from our database
public ActionResult Test()
{
    storeRepository.BeginTransaction();

    var barginBasin = storeRepository.Get( s => s.Name == "Bargin Basin" ).SingleOrDefault();

    if (barginBasin == null)
    {
        storeRepository.Rollback();

        return View( "Error" );
    }

    try
    {
        barginBasin.Name = "Bargain Basin";
    
        storeRepository.Commit();

        return RedirectToAction( "Index" );
    }
    catch
    {
        storeRepository.Rollback();

        return View( "Error" );
    }
}

// Adds sample data to our database
public ActionResult Seed()
{
    // Create a couple of Stores each with some Products and Employees
    var barginBasin = new Store { Name = "Bargin Basin" };
    var superMart = new Store { Name = "SuperMart" };

    var potatoes = new Product { Name = "Potatoes", Price = 3.60 };
    var fish = new Product { Name = "Fish", Price = 4.49 };
    var milk = new Product { Name = "Milk", Price = 0.79 };
    var bread = new Product { Name = "Bread", Price = 1.29 };
    var cheese = new Product { Name = "Cheese", Price = 2.10 };
    var waffles = new Product { Name = "Waffles", Price = 2.41 };

    var daisy = new Employee { FirstName = "Daisy", LastName = "Harrison" };
    var jack = new Employee { FirstName = "Jack", LastName = "Torrance" };
    var sue = new Employee { FirstName = "Sue", LastName = "Walkters" };
    var bill = new Employee { FirstName = "Bill", LastName = "Taft" };
    var joan = new Employee { FirstName = "Joan", LastName = "Pope" };

    // Add Products to the Stores
    // The Store-Product relationship is many-to-many
    AddProductsToStore( barginBasin, potatoes, fish, milk, bread, cheese );
    AddProductsToStore( superMart, bread, cheese, waffles );

    // Add Employees to the Stores
    // The Store-Employee relationship is one-to-many
    AddEmployeesToStore( barginBasin, daisy, jack, sue );
    AddEmployeesToStore( superMart, bill, joan );
    
    storeRepository.BeginTransaction();

    try
    {
        storeRepository.SaveOrUpdateAll( barginBasin, superMart );
    
        storeRepository.Commit();

        return RedirectToAction( "Index" );
    }
    catch
    {
        storeRepository.Rollback();

        return View( "Error" );
    }
}

You can now run your application. If you get any errors, make sure you have an empty database and a valid connection string. In that case, see my previous article for instructions on setting that up. If all you see is the word “Index,” it’s because you don’t have any data in your database yet. In your browser, navigate to the Seed action of the home controller. You should then see “Index” at the top followed by a list of stores, products and employees.

Next time, we’ll look as using NUnit and Moq for unit testing. Surprisingly, it’s relatively easy! As always, let me know if you have any difficulties. Good luck!

Fluent NHibernate, auto mappings and ASP.NET MVC 3

In my previous article, I demonstrated how to use Fluent NHibernate with auto mappings. After that, my plan was to move the code into an ASP.NET MVC 3 application. I assumed it would be relatively simple, which goes to show just how little I know about these things. Anyways, hopefully someone else out there will be able to learn from my experience.

Here’s what the completed project will look like:

Create a new ASP.NET MVC 3 web application called FluentNHibernateMvc3 in Microsoft Visual Studio 2010 and use the empty project template. Next, right click on the project in the Solution Explorer and choose Manage NuGet Packages… Search the online gallery for Fluent NHibernate and install it.

EDIT 12/18/2012: You can get the source code on GitHub.

Once you’ve installed Fluent NHibernate, copy the Employee, Product and Store classes from the Entities folder of our previous project to the Models folder of our current project. Make sure you change the namespace in each file accordingly.

Next, create a new controller called HomeController in the Controllers folder. Since my goal is to move the code from our previous project to our new project with as little changes as possible, the HomeController class will look very similar to the Program class with the following exceptions:

  1. We’ll move the NHibernate specific methods to a new custom HTTP module.
  2. We’ll use a repository to create a layer of abstraction between our main application and our persistence layer.
  3. We’ll split the Main method into two actions: the Index action, which will display the data, and the Seed action, which will add sample data to our database. This is because we don’t want to add sample data every time our application runs.

Here’s a rough skeleton of the home controller:

namespace FluentNHibernateMvc3.Controllers
{
    public class HomeController : Controller
    {
        private readonly IRepository<Store> storeRepository;
        
        // Constructs our home controller
        public HomeController() { }
        
        // Gets all the stores from our database and returns a view that displays them
        public ActionResult Index() { }
        
        // Adds sample data to our database
        public ActionResult Seed() { }
        
        // AddProductsToStore and AddEmployeesToStore methods go here...
    }
}

The first thing you should notice is that the home controller has a field called storeRepository, which implements an IRepository of type Store. This needs to be set in the constructor method:

// Constructs our home controller
public HomeController()
{
    storeRepository = new Repository<Store>();
}

We’ll create the Repository class and IRepository interface later.

Next, we’ll move the bulk of the Main method from our previous project to the Seed action here:

// Adds sample data to our database
public ActionResult Seed()
{
    // Create a couple of Stores each with some Products and Employees
    var barginBasin = new Store { Name = "Bargin Basin" };
    var superMart = new Store { Name = "SuperMart" };

    var potatoes = new Product { Name = "Potatoes", Price = 3.60 };
    var fish = new Product { Name = "Fish", Price = 4.49 };
    var milk = new Product { Name = "Milk", Price = 0.79 };
    var bread = new Product { Name = "Bread", Price = 1.29 };
    var cheese = new Product { Name = "Cheese", Price = 2.10 };
    var waffles = new Product { Name = "Waffles", Price = 2.41 };

    var daisy = new Employee { FirstName = "Daisy", LastName = "Harrison" };
    var jack = new Employee { FirstName = "Jack", LastName = "Torrance" };
    var sue = new Employee { FirstName = "Sue", LastName = "Walkters" };
    var bill = new Employee { FirstName = "Bill", LastName = "Taft" };
    var joan = new Employee { FirstName = "Joan", LastName = "Pope" };

    // Add Products to the Stores
    // The Store-Product relationship is many-to-many
    AddProductsToStore( barginBasin, potatoes, fish, milk, bread, cheese );
    AddProductsToStore( superMart, bread, cheese, waffles );

    // Add Employees to the Stores
    // The Store-Employee relationship is one-to-many
    AddEmployeesToStore( barginBasin, daisy, jack, sue );
    AddEmployeesToStore( superMart, bill, joan );

    storeRepository.SaveOrUpdateAll( barginBasin, superMart );

    return RedirectToAction( "Index" );
}

There are a few important changes you should notice:

  1. We don’t create a new session factory in the Seed action, or anywhere else in the home controller for that matter.
  2. We don’t open a session here.
  3. We don’t create or commit a transaction.

These tasks will be handled by our custom HTTP module at the beginning and end of each web request. Separating these tasks allows us to minimize the dependencies in our home controller, which is often referred to as loose coupling. Our controller doesn’t know anything about sessions or transactions – it isn’t even aware of NHibernate!

The Index action is very simple:

// Gets all the stores from our database and returns a view that displays them
public ActionResult Index()
{
    var stores = storeRepository.GetAll();

    return View( stores.ToList() );
}

Here, we call the GetAll method of our repository, cast the result to a list and send the list to the view. The Index view should go in your Views/Home folder and should look like this:

@model List<FluentNHibernateMvc3.Models.Store>

@{
    ViewBag.Title = "Index";
}

<h2>Index</h2>

<ul>
    @foreach ( var store in Model ) {
        <li>@store.Name</li>
        <ul>
            <li>Products:</li>
            <ul>
                @foreach ( var product in store.Products ) {
                    <li>@product.Name</li>
                }
            </ul>
            <li>Staff:</li>
            <ul>
                @foreach ( var employee in store.Staff ) {
                    <li>@employee.FirstName @employee.LastName</li>
                }
            </ul>
        </ul>
    }
</ul>

Now, let’s tackle that repository. Place these files in a new folder called Repositories at the root level of the project. This is where we’ll define what exactly the GetAll and SaveOrUpdateAll methods do that we’re using in our controller actions. First, create the interface:

namespace FluentNHibernateMvc3.Repositories
{
    public interface IRepository<T>
    {
        IQueryable<T> GetAll();
        IQueryable<T> Get( Expression<Func<T, bool>> predicate );
        IEnumerable<T> SaveOrUpdateAll( params T[] entities );
        T SaveOrUpdate( T entity );
    }
}

Then create the implementation:

namespace FluentNHibernateMvc3.Repositories
{
    public class Repository<T> : IRepository<T>
    {
        private readonly ISession session;

        public Repository()
        {
            session = NHibernateSessionPerRequest.GetCurrentSession();
        }

        public IQueryable<T> GetAll()
        {
            return session.Query<T>();
        }

        public IQueryable<T> Get( Expression<Func<T, bool>> predicate )
        {
            return GetAll().Where( predicate );
        }

        public IEnumerable<T> SaveOrUpdateAll( params T[] entities )
        {
            foreach ( var entity in entities )
            {
                session.SaveOrUpdate( entity );
            }

            return entities;
        }

        public T SaveOrUpdate( T entity )
        {
            session.SaveOrUpdate( entity );

            return entity;
        }
    }
}

Speaking of loose coupling, our repository doesn’t know anything about session factories or transactions, but it does have a session field that implements ISession. This field is set by calling the GetCurrentSession method of our custom HTTP module, which we’ll name NHibernateSessionPerRequest.

Here’s an outline of the NHibernateSessionPerRequest class, which you can put in a new Modules folder at the root level of the project:

namespace FluentNHibernateMvc3.Modules
{
    /// 
    /// http://www.bengtbe.com/blog/2009/10/08/nerddinner-with-fluent-nhibernate-part-3-the-infrastructure
    /// 
    public class NHibernateSessionPerRequest : IHttpModule
    {
        private static readonly ISessionFactory sessionFactory;

        // Constructs our HTTP module
        static NHibernateSessionPerRequest() { }
        
        // Initializes the HTTP module
        public void Init( HttpApplication context ) { }

        // Disposes the HTTP module
        public void Dispose() { }

        // Returns the current session
        public static ISession GetCurrentSession() { }

        // Opens the session, begins the transaction, and binds the session
        private static void BeginRequest( object sender, EventArgs e ) { }

        // Unbinds the session, commits the transaction, and closes the session
        private static void EndRequest( object sender, EventArgs e ) { }

        // Returns our session factory
        private static ISessionFactory CreateSessionFactory() { }

        // Returns our database configuration
        private static MsSqlConfiguration CreateDbConfig()

        // Returns our mappings
        private static AutoPersistenceModel CreateMappings()

        // Updates the database schema if there are any changes to the model,
        // or drops and creates it if it doesn't exist
        private static void UpdateSchema( Configuration cfg ) { }
    }
}

Notice that the sessionFactory field, which implements ISessionFactory, is static. Session factories can be expensive to create, especially with a large domain model. So we only want to instantiate one of these during the lifetime of our app, which will hang around in memory until our app dies:

// Constructs our HTTP module
static NHibernateSessionPerRequest()
{
    sessionFactory = CreateSessionFactory();
}

// Returns our session factory
private static ISessionFactory CreateSessionFactory()
{
    return Fluently.Configure()
        .Database( CreateDbConfig )
        .Mappings( m => m.AutoMappings.Add( CreateMappings() ) )
        .ExposeConfiguration( UpdateSchema )
        .CurrentSessionContext<WebSessionContext>()
        .BuildSessionFactory();
}

// Returns our database configuration
private static MsSqlConfiguration CreateDbConfig()
{
    return MsSqlConfiguration
        .MsSql2008
        .ConnectionString( c => c.FromConnectionStringWithKey( "testConn" ) );
}

// Returns our mappings
private static AutoPersistenceModel CreateMappings()
{
    return AutoMap
        .Assembly( System.Reflection.Assembly.GetCallingAssembly() )
        .Where( t => t.Namespace != null && t.Namespace.EndsWith( "Models" ) )
        .Conventions.Setup( c => c.Add( DefaultCascade.SaveUpdate() ) );
}

// Updates the database schema if there are any changes to the model,
// or drops and creates it if it doesn't exist
private static void UpdateSchema( Configuration cfg )
{
    new SchemaUpdate( cfg )
        .Execute( false, true );
}

Most of these methods can be copied to this class from our previous project. There are only a few changes:

  1. We’ve replaced the DropCreateSchema method with a new method called UpdateSchema. As the name suggests, this method will only create the database schema if it doesn’t already exist. Otherwise, it will update it from the model.
  2. NHibernate needs to be told what type of context it’s running in. We do that by calling the CurrentSessionContext extension method in our fluent configuration. It’s strongly typed, so we give it a type of WebSessionContext.
  3. Instead of building a connection string in the CreateDbConfig method, I’m using a connection string from the Web.config file. You can do it either way.
  4. The CreateMappings method will create auto mappings for all types in our assembly that have a namespace ending in “Models”. This is preferable over matching the entire namespace, since it will require less changes moving forward.

Here are the remaining methods:

// Initializes the HTTP module
public void Init( HttpApplication context )
{
    context.BeginRequest += BeginRequest;
    context.EndRequest += EndRequest;
}

// Disposes the HTTP module
public void Dispose() { }

// Returns the current session
public static ISession GetCurrentSession()
{
    return sessionFactory.GetCurrentSession();
}

// Opens the session, begins the transaction, and binds the session
private static void BeginRequest( object sender, EventArgs e )
{
    ISession session = sessionFactory.OpenSession();

    session.BeginTransaction();

    CurrentSessionContext.Bind( session );
}

// Unbinds the session, commits the transaction, and closes the session
private static void EndRequest( object sender, EventArgs e )
{
    ISession session = CurrentSessionContext.Unbind( sessionFactory );

    if ( session == null ) return;

    try
    {
        session.Transaction.Commit();
    }
    catch ( Exception )
    {
        session.Transaction.Rollback();
    }
    finally
    {
        session.Close();
        session.Dispose();
    }
}

Previously, we weren’t catching any exceptions when we tried to commit our transaction. Wrapping our call to commit in a try-catch statement gives us a chance to rollback if something goes wrong.

We’re almost done! We still need to register our custom HTTP module in IIS, so that it can receive and process HTTP requests. If you are using IIS 6.0 or IIS 7.0 in classic mode, add this to your Web.config file:

<configuration>
  <system.web>
    <httpModules>
      <add name="NHibernateSessionPerRequest" type="FluentNHibernateMvc3.Modules.NHibernateSessionPerRequest" />
     </httpModules>
  </system.web>
</configuration>

If you are using IIS 7.0 in integrated mode, add this to your Web.config file:

<configuration>
  <system.webServer>
    <modules>
      <add name="NHibernateSessionPerRequest" type="FluentNHibernateMvc3.Modules.NHibernateSessionPerRequest" />
    </modules>
  </system.webServer>
</configuration>

Finally, if you decided not to build a connection string in the CreateDbConfig method, you’ll need to add one under the configuration section of your Web.config file. Here’s mine, which is using SQL Server 2008:

<connectionStrings>
  <add name="testConn" connectionString="Server=testServer;Database=testDB;User ID=testUser;Password=testPass" providerName="System.Data.SqlClient" />
</connectionStrings>

Before running the application, make sure you create an empty database, and replace “testServer”, “testDB”, “testUser” and “testPass” with your actual server, database, username, and password.

When you run the application, you should see this:

Index

Not very exciting, it is? That’s because we haven’t added any data to the database yet! In your browser, navigate to the Seed action of the home controller, i.e. append /Home/Seed to the URL in your browser’s address bar. You should see this:

Index

  • Bargin Basin
    • Products:
      • Potatoes
      • Fish
      • Milk
      • Bread
      • Cheese
    • Staff:
      • Daisy Harrison
      • Jack Torrance
      • Sue Walkters
  • SuperMart
    • Products:
      • Bread
      • Cheese
      • Waffles
    • Staff:
      • Bill Taft
      • Joan Pope

Look familiar? It should if you read my previous article.

I’d like to demonstrate one more thing before I sign off. Add the following action to the home controller:

// Gets and modifies a single store from our database
public ActionResult Test()
{
    var barginBasin = storeRepository.Get( s => s.Name == "Bargin Basin" ).SingleOrDefault();

    if ( barginBasin == null )
    {
        return RedirectToAction( "Index" );
    }

    barginBasin.Name = "Bargain Basin";

    return RedirectToAction( "Index" );
}

This action is fairly self-explanatory: It will find the Store record named “Bargin Basin” and rename it to “Bargain Basin.” The cool part is that we don’t have to manually save anything because it’s all taken care of by our repository and HTTP module! Navigate to the Test action of the home controller in your browser and you’ll see what I mean.

That does it for this article. Next time, I’ll cover unit testing and dependency injecting using Castle Windsor.

How to use Fluent NHibernate with auto mappings

For this article, I’ll be modifying “Your First Project” found on the Fluent NHibernate Wiki: Getting Started page. I’ll also borrow a couple of ideas from FlashM’s article on Dream.In.Code. The idea is to take advantage of the auto mappings feature of Fluent NHibernate, which is not documented very well, even though it’s arguably its strongest selling point.

Here’s what the completed project will look like:

To begin, create a new console application called FluentNHibernateConsole in Microsoft Visual Studio 2010. Next, right click on the project in the Solution Explorer and choose Manage NuGet Packages… Search the online gallery for Fluent NHibernate and install it.

EDIT 12/18/2012: I finally managed to get the source code on GitHub!

Next, create a new folder in your project and name it Entities. Place the following classes in your Entities folder:

namespace FluentNHibernateConsole.Entities
{
    public class Employee
    {
        public virtual int Id { get; protected set; }
        public virtual string FirstName { get; set; }
        public virtual string LastName { get; set; }
        public virtual Store Store { get; set; }
    }
}

Before Fluent NHibernate version 1.3.0.717, we could make the setter function of the Id property private instead of protected. The reason it needs to be one or the other is because it should never be changed by the code. Instead, it should only ever be touched by NHibernate.

namespace FluentNHibernateConsole.Entities
{
    public class Product
    {
        public virtual int Id { get; protected set; }
        public virtual string Name { get; set; }
        public virtual double Price { get; set; }
        public virtual IList<Store> StoresStockedIn { get; protected set; }

        public Product()
        {
            StoresStockedIn = new List<Store>();
        }
    }
}

Not only should the Id property of the Product class be protected, but the StoresStockedIn property should be as well. Once this list is populated, we should never be able to set it since that would create orphaned Store records.

namespace FluentNHibernateConsole.Entities
{
    public class Store
    {
        public virtual int Id { get; protected set; }
        public virtual string Name { get; set; }
        public virtual IList<Product> Products { get; protected set; }
        public virtual IList<Employee> Staff { get; protected set; }

        public Store()
        {
            Products = new List<Product>();
            Staff = new List<Employee>();
        }

        public virtual void AddProduct( Product product )
        {
            product.StoresStockedIn.Add( this );
            Products.Add( product );
        }

        public virtual void AddEmployee( Employee employee )
        {
            employee.Store = this;
            Staff.Add( employee );
        }
    }
}

Here’s an outline of the Program class:

namespace FluentNHibernateConsole
{
    public class Program
    {
        // Adds sample data to our database and writes the data to the console
        static void Main() { }

        // Returns our session factory
        private static ISessionFactory CreateSessionFactory() { }

        // Returns our database configuration
        private static MsSqlConfiguration CreateDbConfig()

        // Returns our mappings
        private static AutoPersistenceModel CreateMappings() { }

        // Drops and creates the database schema
        private static void DropCreateSchema( Configuration cfg) { }

        // Writes the store data, along with its associated products and employees, to the console
        private static void WriteStorePretty( Store store ) { }

        // Adds any products that we pass in to the store that we pass in
        public static void AddProductsToStore( Store store, params Product[] products ) { }

        // Adds any employees that we pass in to the store that we pass in
        public static void AddEmployeesToStore( Store store, params Employee[] employees ) { }
    }
}

WriteStorePretty, AddProductsToStore and AddEmployeesToStore methods are all fairly self-explanatory:

// Writes the store data, along with its associated products and employees, to the console
private static void WriteStorePretty( Store store )
{
    Console.WriteLine( store.Name );
    Console.WriteLine( " Products:" );

    foreach ( var product in store.Products )
    {
        Console.WriteLine( " " + product.Name );
    }

    Console.WriteLine( " Staff:" );

    foreach ( var employee in store.Staff )
    {
        Console.WriteLine( " " + employee.FirstName + " " + employee.LastName );
    }

    Console.WriteLine();
}

// Adds any products that we pass in to the store that we pass in
public static void AddProductsToStore( Store store, params Product[] products )
{
    foreach ( var product in products )
    {
        store.AddProduct( product );
    }
}

// Adds any employees that we pass in to the store that we pass in
public static void AddEmployeesToStore( Store store, params Employee[] employees )
{
    foreach ( var employee in employees )
    {
        store.AddEmployee( employee );
    }
}

In the Main method, we open a session factory, then begin a transaction. At the end of the transaction, we save the session and commit the transaction:

// Adds sample data to our database and writes the data to the console
static void Main()
{
    // Create a session factory
    var sessionFactory = CreateSessionFactory();

    // Open a session
    using ( var session = sessionFactory.OpenSession() )
    {
        // Begin a transaction
        using ( var transaction = session.BeginTransaction() )
        {
            // Create a couple of Stores each with some Products and Employees
            var barginBasin = new Store { Name = "Bargin Basin" };
            var superMart = new Store { Name = "SuperMart" };

            var potatoes = new Product { Name = "Potatoes", Price = 3.60 };
            var fish = new Product { Name = "Fish", Price = 4.49 };
            var milk = new Product { Name = "Milk", Price = 0.79 };
            var bread = new Product { Name = "Bread", Price = 1.29 };
            var cheese = new Product { Name = "Cheese", Price = 2.10 };
            var waffles = new Product { Name = "Waffles", Price = 2.41 };

            var daisy = new Employee { FirstName = "Daisy", LastName = "Harrison" };
            var jack = new Employee { FirstName = "Jack", LastName = "Torrance" };
            var sue = new Employee { FirstName = "Sue", LastName = "Walkters" };
            var bill = new Employee { FirstName = "Bill", LastName = "Taft" };
            var joan = new Employee { FirstName = "Joan", LastName = "Pope" };

            // Add Products to the Stores
            // The Store-Product relationship is many-to-many
            AddProductsToStore( barginBasin, potatoes, fish, milk, bread, cheese );
            AddProductsToStore( superMart, bread, cheese, waffles );

            // Add Employees to the Stores
            // The Store-Employee relationship is one-to-many
            AddEmployeesToStore( barginBasin, daisy, jack, sue );
            AddEmployeesToStore( superMart, bill, joan );

            // Save the session
            session.SaveOrUpdate( barginBasin );
            session.SaveOrUpdate( superMart );

            // Commit the transaction
            transaction.Commit();
        }

        // Begin a transaction
        using ( var transaction = session.BeginTransaction() )
        {
            var stores = session.CreateCriteria( typeof( Store ) )
                .List();

            foreach ( var store in stores )
            {
                WriteStorePretty( store );
            }

            // Commit the transaction
            transaction.Commit();
        }
    }

    Console.ReadKey();
}

This hard dependency on NHibernate isn’t a best practice, but it will do for now.

The CreateSessionFactory method is where we get into the configuration of Fluent NHibernate:

// Returns our session factory
private static ISessionFactory CreateSessionFactory()
{
    return Fluently.Configure()
        .Database( CreateDbConfig )
        .Mappings( m => m.AutoMappings.Add( CreateMappings() ) )
        .ExposeConfiguration( DropCreateSchema )
        .BuildSessionFactory();
}

There are four steps to our fluent configuration. First, we configure our database connection with a call to the CreateDbConfig method:

// Returns our database configuration
private static MsSqlConfiguration CreateDbConfig()
{
    return MsSqlConfiguration
        .MsSql2008
        .ConnectionString( c => c
            .Server( "testServer" )
            .Database( "testDB" )
            .Username( "testUser" )
            .Password( "testPass" );
}

Before running the application, make sure you create an empty database, and replace “testServer”, “testDB”, “testUser” and “testPass” with your actual server, database, username, and password. Note that I’m using SQL Server 2008, but you can use SQLite, MySQL, or any other supported database. You can also read the connection string from a settings file, which you can read more about on the Fluent NHibernate Wiki.

Next, we configure our mappings with a call to the CreateMappings method:

// Returns our mappings
private static AutoPersistenceModel CreateMappings()
{
    return AutoMap
        .Assembly( System.Reflection.Assembly.GetCallingAssembly() )
        .Where( t => t.Namespace == "FluentNHibernateConsole.Entities" )
        .Conventions.Setup( c => c.Add( DefaultCascade.SaveUpdate() ) );
}

Normally, NHibernate uses XML files to determine how each entity in the domain model relates to each table in the database. Fluent NHibernate allows us to bypass this laborious step with auto mappings. We can add other conventions here, but all we need to get our application running is to turn cascading on. This way, when we save a Store, all the associated Products and Employees are saved too.

Next, we tell NHibernate to drop and create our database schema each time the application runs:

// Drops and creates the database schema
private static void DropCreateSchema( Configuration cfg )
{
    new SchemaExport( cfg )
        .Create( false, true );
}

This step is optional. If you prefer, you can the database schema manually. You can also tell NHibernate to update the schema only when the model changes:

// Updates the database schema if there are any changes to the model
private static void UpdateSchema( Configuration cfg )
{
    new SchemaUpdate( cfg );
}

Finally, we build the session factory. This is the last step in our fluent configuration.

We can now run the application. When you do so, you should see this:

If this is what you see, then congratulations on completing your first Fluent NHibernate project with auto mappings! If not, drop me a comment and we’ll try to get it figured out. I’m pretty new to this too, so don’t be afraid to ask!