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For this post we are going to enable auto registration in the container and see what benefits it can bring us.

What is auto registration?

What we mean by this is that we would like all our controllers and all the services those controllers depend on (and any dependencies they may have) to be automatically registered into the container for us. This saves us the extra step of manually registering them in the xml configuration.

The ability to auto register components into the container should be available in the last castle release (I haven’t checked to be honest) but what I want to show is the reduced friction way of enabling this. To do this we need to grab one of the later builds of castle.

Getting the latest castle builds

The castle project publishes all builds to http://builds.castleproject.org (which at the time of writing this just happens to be down at the moment which is the first time I’ve ever seen it down). On here you will see all successful and failed builds. If you explore the details of any of these builds you’ll also see a whole load of unit tests that are run as part of the build. This is a practice that I highly recommend following.

For this example I’ve grabbed build 967. Unzip the contents of the build and copy the bin folder contents into your tools/castle directory.

Before running the application there are two slight changes that need to be made. The first one is that when using later builds you will get an error when you navigate to your site with “Could not load type ‘Castle.MonoRail.Framework.EngineContextModule’ from assembly ‘Castle.MonoRail.Framework’“. To fix this, edit the web.config and remove the ‘monorail’ Http Module from the system.web/httpModules section.

The other change is with the windsor integration. A change was made to the windsor extension called RailsFacility which is now called MonoRailFacility instead. Make this change within the facilities.config file.

With these slight changes in place we should be able to now build and run our application.

So now onto the real guts of this post.

What we want to first do is auto register all our controllers. Each of our controllers is ultimately an IController so what we really want to do is auto register all IController classes into the container.

We do this within GlobalApplication.cs (the codebehind for global.asax) within the Application_OnStart method. You’ll already see that this is where the container get’s initialised for the whole application, passing in a new instance of XmlInterpreter with no parameters which tells windsor to look in web.config for the configuration.

public void Application_OnStart()
{
    container = new WindsorContainer(new XmlInterpreter());
}

We then add the following line beneath this to get windsor to automatically register all controllers:

container.Register(
    AllTypes.Of<IController>()
    .FromAssembly(Assembly.GetExecutingAssembly()));

Hmm – a nice bit of fluent interface goodness there. So here we are looking for all types of IController from the executing assembly and registering them into the container.

If we build and run our application everything works as it should but there’s a little gotcha (it’s actually a good gotcha) in that this new line of code won’t do much for us right now as we are still explicitly registering our controllers in the controllers.config file. The container still loads and resolves item in the config files first. When the auto registration code is invoked it will skip over any controllers that have already been explicitly registered manually. This enables us to override the auto registration so we still have flexibility when we need it.

So if we now go into our controllers.config and remove all the existing controller registrations and rerun the application there should be no change and now all our controllers are being auto registered.

If we now run our application then our BookController is still retrieved from the container (as it was auto registered) and the container is still satisfying it’s dependency on the BookRepository (as it is still manually registered).

To get our services (and other components) auto registered we make a further change to GlobalApplication.cs and add the following:

public void Application_OnStart()
{
    container = new WindsorContainer(new XmlInterpreter());
    container.Register(
        AllTypes.Of<IController>()
        .FromAssembly(Assembly.GetExecutingAssembly()));
    container.Register(
        AllTypes.Pick()
        .FromAssembly(Assembly.GetExecutingAssembly())
        .WithService.FirstInterface());
}

Here we’re now selecting all types from the executing assembly (our web app) and registering them into the container. We are also specifying WithService.FirstInterface. What this enables is that for any types that implement an interface, use the first interface as the ‘service’ to register the type against.

If we introduce an IBookRepository interface (something we will do at some point btw) and changed BookRepository to implement this interface then as long as IBookRepository was the first interface BookRepository implemented then it would be registered into the container against that interface.

So if we changed our BookController to depend on IBookRepository then it would all still be auto registered and wired up correctly as we expect.

This is actually one of the great things with using auto registration in that we can make this changes without having to manually change the configuration. It also allows us to add new controllers, again without having to worry about the manual configuration changes. This allows us to focus on coding and providing a solution in a more friction free manner.

Now to test our application. First off, change components.config to remove our manual BookRepository configuration.

As you should see, our application loads and runs as it did before but now with our controllers, services and supporting components all auto registered for us.

Next steps

So far we haven’t explored the benefits of Monorail in regards to unit testing, and we’ve mentioned about introducing IBookRepository which will give us some flexibility to our implementations. I’m intending that one of those implementations will be using NHibernate and we’ll be using Fluent NHibernate to handle our mapping for us. Let’s see if I can pull those out of the bag quicker than I’ve pulled this one out 🙂

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We’ve now run through the initial wizard to get our starting Monorail application up and running. We’re now going to explore what the wizard has generated for us.

Solution StructureSolutionExplorer

Here’s our generated solution with our web project and our test project. Monorail is an MVC web framework and the wizard has generated a project structure for us for containing our Models, Views and Controllers. We also have a folder for static content and the Windsor integration has given us a config folder.

Our Models folder contains our starting business objects/entities. As our application grows, these might get pushed out into their own project to form a domain model or they may stay as a presentation model. For now we’ll gloss over them a little at least until we explore Castle Active Record.

The views and controllers have a linked structure as each controller has a corresponding folder under the views folder. These individual view folders then contain a .vm file for each action that can be performed on the controller. These .vm files are the NVelocity templates and contain our presentation only, including some lightweight presentation logic to loop over collections or other presentation specific operations.

Now, looking at the controllers folder we have 3 controllers listed (Contact, Home and Login) along with BaseController. If we look further we can see that each of the 3 controllers inherits from BaseController, which in turn inherits from SmartDispatcherController. In Monorail, a controller is a class that inherits from Controller but usually you will use the SmartDispatcherController as this provides us with some very powerful data binding capabilities.

A closer look at a controller

OK, so let’s crack open one of our starting controllers and see what we can find. Since we are on the home/index.castle page then let’s pick on the HomeController as this is the one that maps to our current page.

Looking inside HomeController we have 2 public methods called Index and BlowItAway. Both are actions on the controller and our current page of home/index.castle maps to the Index method.

Within the Index method we see an assignment to PropertyBag. The PropertyBag is one of a couple of ways of passing information over to a view from the controller. By assigning DateTime.Now to PropertyBag[“AccessDate”] we are giving the view the current time via a view variable of “AccessDate”. If we open up the Views/Home/Index.vm file we can use this variable. Find the <div id=”greeting”> line and add the following new div below it:

<div>The time is $AccessDate</div>

Save the Index.vm file and refresh your browser. You should now see the date and time output. At the moment it doesn’t look very pretty but notice how we’ve output a dynamic variable without jumping through the usual ASP.NET escaping into server code in the page. Our usual way of doing this would be something like <div>The time is <%= DateTime.Now %></div>.

Not only that, but we haven’t embedded the logic of using DateTime.Now within the page itself. The controller is where we decide this type of logic and the view itself remains very light. In my mind this is one of the big benefits of using Monorail, it is naturally guiding us to separate our logic from our views. This is possible with web forms but it’s something we have to enforce ourselves and it is very easy to slip back into bad habits (well, it is for me anyway).

But now lets fix the ugly nature of our date time format. Change the view code to <div>The time is $AccessDate.ToString(‘HH:mm’)</div>. Now we get just the time output. NVelocity is dynamically calling the ToString for us.

But have we just mixed logic that the controller should be handling for us? That depends. If it’s something that needs to be enforced and testable then keep the view light and just output $AccessDate and change the controller to push the correctly formatted time into the property bag.

OK – this wraps it up for our explore of the starting application for now. For our next post we’ll add a new controller and wire it up with Windsor.

I’m planning on this being a start of a series of posts on Monorail, the MVC web framework from the Castle Project (www.castleproject.org). So, how to get started with Castle Monorail.

The first starting point is to download the last full release which is 1.0 Release Candidate 3. This is the first potential stumbling block for many in that it is a release candidate rather than a full release and has remained in this state since September 2007. However, the whole castle stack is, from my experience, very stable with a whole array of tests and is actively being developed.

Once downloaded, install and you should now have all the binaries etc located under C:\Program Files\CastleProject. This includes the Visual Studio integration to provide a Monorail and Active Record project types to get you started (although only available for VS2005 at this point in time).

Now, fire up VS2005 and create a new project. Select Visual C#->Castle Monorail Project. This will start up the Monorail project wizard.

Castle VS Wizard 1st Screen

For an initial getting started we’ll stick with the NVelocity view engine but we’ll enable Windsor integration as we’ll lean on this in a following post. We’ll also ignore the routing engine for two reasons. For one, we don’t really need it right now, and the other more important reason is that it causes an error with the end project. OK, next screen.

Castle VS Wizard 2nd Screen

For now, we’ll ignore these options but we’ll come back to the Active Record Integration in a later post.

Castle VS Wizard Last Screen

The last wizard screen asks us if we are a TDD enthusiast and if selected gives us a separate test project using NUnit as the test framework. Keep this option selected and hit Finish.

We now have our starting Monorail project. To see it in action select the properties of the project and set the web properties to use either IIS or the VS Development Server and hit F5.

Monorail Starting Application 

You should get the homepage as above. This is the starting Monorail application generated by the wizard and gives us everything we need for starting out with Monorail and the ending point for this blog post. Further posts will explore the different elements of Monorail, its testability and the Windsor integration.