SEO with ASP.NET MVC
ASP.NET MVC meet SEO; SEO meet ASP.NET MVC
Mar 3rd
Whilst ASP.NET is clearly the best thing to hit .NET web development in a long-time it seems like the framework itself is somewhat challenged when it comes to SEO. For starters the concept of a page has all but disappeared – sure you can have a ViewPage but there’s no code associated with it. And sure, you have ASP.NET Routing so you can do anything you like with routes but the catchall route {Controller}/{Action}/{id} is as much a liability as it is a benefit as it catches things you really didn’t want it to catch and generates routes you really didn’t want to generate all too easily.
Convention over configuration is nice and all that, but sometimes a bit of configuration is necessary to bring your house into order, especially when the convention doesn’t allow things you really want for SEO.
So let’s take a look at all the things we really want to be able to do when creating an SEO friendly web site and see how we can get ASP.NET MVC to handle them.
For SEO we need:-
1. The ability to define a canonical url for a page. To use that canonical URL whenever we generate a route. To include that canonical url in the page header to instruct search engines that this is the canonical url for that page.
2. The ability to define multiple alternate URLs for a page. Plans change and your site changes too but you don’t want 404 errors, you want the user to land on the same page even if you changed the URL to improve its SEO keyword content for example. Ideally you’d like to 301 redirect these legacy urls but having them at least display the right page and including the canonical url in the header for that page is good enough.
3. The ability to use hyphens in urls. But since Controllers are classes and Actions are methods and the convention is to use them as parts of the URL this isn’t supported out of the box.
4. The ability to define title, meta description and meta keywords tags for a page in such a way that you can enforce rules around them such as requiring every public page to have a title tag, or ensuring that the length of the title tag is reasonable, or ensuring that your product name is on the end of every title tag.
5. The ability to build a sitemap.xml file that we can submit to Google or Bing containing every URL that we want them to index.
In my next few posts I’ll explain how we can overcome all of these shortcomings of ASP.NET MVC to create a great SEO-friendly web site.
Stay tuned!
Building sitemap.xml for SEO ASP.NET MVC
Feb 9th
Creating a sitemap.xml file for Google and other search engines can be accomplished in MVC using a simple ActionResult that returns the appropriate XML blog. The problem however is in generating the list of URLs to go into that sitemap.xml file.
In ASP.NET MVC there is no distinction between an action method that is a page and one that is a service call. To remedy that let’s create an ActionFilterAttribute that can be applied to any method to mark it as a page and to record the URL that we want that page to show up as in our sitemap:
1 /// <summary>
2 /// This attribute indicates that a method is an actual page and gives the data for it
3 /// </summary>
4 [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, Inherited = true, AllowMultiple = false)]
5 public class MVCUrlAttribute : ActionFilterAttribute
6 {
7 public string Url { get; private set; }
8
9 public MVCUrlAttribute(string url)
10 {
11 this.Url = url;
12 }
13
14 public override void OnResultExecuting(ResultExecutingContext filterContext)
15 {
16 string fullyQualifiedUrl = filterContext.HttpContext.Request.Url.GetLeftPart(UriPartial.Authority) + this.Url;
17 // We build HTML here because we want the View to be easily able to include it without any conditionals
18 // and because the ASP.NET WebForms view engine sometimes doesn’t subsitute <% in certain head items
19 filterContext.Controller.ViewData["CanonicalUrl"] = @”<link rel=”"canonical”" href=”"” + fullyQualifiedUrl + ” />”;
20 base.OnResultExecuting(filterContext);
21 }
22 }
You may wonder at this point why we can’t just use the Routing table to figure this out. The issue is that multiple routes may map onto one page but we still want it to show up just once in the sitemap otherwise we will get slammed for duplicate content. We also want to be able to mark each page with its canonical URL.
Now we can use reflection to find all of the ‘pages’ in our ASP.NET MVC Application and then build a sitemap.xml file from them.
1 List<string> allPageUrls = new List<string>();
2
3 // Find all the MVC Routes
4 Log.Debug(“*** FINDING ALL MVC ROUTES MARKED FOR INCLUSION IN SITEMAP”);
5 var allControllers = Assembly.GetExecutingAssembly().GetTypes().Where(t => t.IsSubclassOf(typeof(Controller)));
6 Log.DebugFormat(“Found {0} controllers”, allControllers.Count());
7
8 foreach (var controllerType in allControllers)
9 {
10 var allPublicMethodsOnController = controllerType.GetMethods(BindingFlags.Public | BindingFlags.Instance);
11 Log.DebugFormat(“Found {0} public methods on {1}”, allPublicMethodsOnController.Count(), controllerType.Name);
12
13 foreach (var publicMethod in allPublicMethodsOnController)
14 {
15 var mvcurlattr = publicMethod.GetCustomAttributes(true).OfType<MVCUrlAttribute>().FirstOrDefault();
16 if (mvcurlattr != null)
17 {
18 string url = mvcurlattr.Url;
19 Log.Debug(“Found “ + controllerType.Name + “.” + publicMethod.Name + ” <– “ + url);
20 allPageUrls.Add(url);
21 }
22 }
23 }