Ubiquitous Technology

The routing enginge that ASP.NET MVC is quite powerful and allows mapping between an URL and the controller and controller action. The routing was originally released in ASP.NET 3.5 SP 1 but I suspect few use it with WebForms. You can easily add new routes and have multiple different routes.

As an example, let's assume we want to have a route where we easily can list various products and also a separate route for events that we offer during various dates. A good piece of advice by Scott Hanselman is to add a comment above your route to make it more clear what the expected route is which I normally do. All the routes are normally wired in the global.asax.

Our first route to display a subcategory will look like this: http://localhost/product/videogames/nintendo . The crafted route will look like this.

// http://localhost/product/category/subcategory
  // http://localhost/product/videogames/nintendo   
  routes.MapRoute(
           "Category",                                              // Route name
           "products/{category}/{subcategory}",                           // URL with parameters
           new
           {
               controller = "Catalog", action = "Index", category = "Listed",
               subcategory = "All Items"
           }
       );

We added defaults for the controller, action, category and subcategory but of course that is optional. Our controllers will accept the category and subcategory and act on it.

Our controller class will need to get the category and subcategory to be able to act on it. Our controller in this example looks like this:

public class CatalogController : Controller
{
   //
   // GET: /Catalog/

   public ActionResult Index(string category, string subcategory)
   {
       ViewData["Message"] = string.Format("Category {0}, Subcategory{1}"
                                       , category, subcategory);
       return View();
   }

}

In our next route, we want it to be displaying a specific event on a specific date and as an example it will look like this: http://localhost/events/2009/05/25 . We will craft it like this:

    // http://localhost/events/year/month/day
   // http://localhost/events/2009/05/25   
   routes.MapRoute(
           "Event",                                              // Route name
           "events/{year}/{month}/{day}",                           // URL with parameters
           new
           {
               controller = "Event",
               action = "Index"
           }
       );      

A corresponding controller that will be handling this request has to be able to handle the year, month and day:

public class EventController : Controller
{
   //
   // GET: /Event/

   public ActionResult Index(string year, string month, string day)
   {
       ViewData["Message"] = string.Format("Event for mm {0} / dd {1} / yyyy {2}"
                                         , month, day, year);
       return View();
   }

}

If you have many routes set up, it may be difficult to figure out why a route isn't being executed as expected. I hope most people by now are familiar with Phil Haack's excellent URL Routing Debugger.

If we try to hit our product URL by incorrectly specifying the URL http://localhost/product, the Routing Debugger shows that the expected route is not being routed correctly.


This can save a ton of time if you have many routes set up in the same project.

The one thing we're still missing is unit tests. We should have started with the unit tests but in this example we're showing the example in reverse order to make the routing mechanism more clear. The ASP.NET MVC framework supports many different unit test and mocking frameworks, I prefer the combination of NUnit and Moq but you can use any of the other supported .Net unit testing/mocking frameworks.

In order to test the routing mechanism, we need to be able to mock the HttpContext. I prefer to use the class MvcMockHelpersthat Scott Hanselman has blogged about instead of writing it from scratch. Our test case for the product route will be quite simple since the plumbing is already done:

using System;
using System.Web;
using System.Web.Routing;
using Moq;
using NUnit.Framework;

[TestFixture]
public class RouteTest
{
    [Test]
    public void Test_If_Product_Route_Returns_Expected_Result()
    {
        RouteCollection routes = new RouteCollection();
        POC_Stuff.MvcApplication.RegisterRoutes(routes);

        var context = MvcMockHelpers.FakeHttpContext("~/products/videogames/nintendo");
        RouteData routeData = routes.GetRouteData(context);

        Assert.That(routeData.Values["category"].ToString() == "videogames");
        Assert.That(routeData.Values["subcategory"].ToString() == "nintendo");
        Assert.That(routeData.Values["controller"].ToString() == "Catalog");
    }
}

We call the RegisterRoute method of the Global.asax to get the actual routes. After we get the fake HttpContext with our URL, we just need to verify if we see the expected result.

There are other ways to set up the routing with some of the other frameworks like MvcContrib which we will look at next time.