Dr Dave

I needed to deal with existing links to my previous blog engine, as well as invalid requests to the new engine.

Legacy Links

As I mentioned previously, my new blog engine has opted for a different URL structure to my old engine. In order to support existing links to my old blog posts, I added some legacy routes to my routing table, as follows:

1. Category links of the format http://{domain}/{directory}/category/{name}.aspx are mapped to my existing controller with the following route:

   routes.MapRoute(
       "MyRoute",
       "category/{name}.aspx",
       new { controller = "MyController", action = "MyAction" });
   

2. Post links of the format http://{domain}/{directory}/post/{name}.aspx are mapped to my existing controller with the following route:

   routes.MapRoute(
       "MyRoute",
       "post/{name}.aspx",
       new { controller = "MyController", action = "MyAction" });
   

3. Month links of the format http://{domain}/{directory}/{year}/{month}/default.aspx are mapped to my existing controller with the following route:

   routes.MapRoute(
       "MyRoute",
       "{year}/{month}/default.aspx",
       new { controller = "MyController", action = "MyAction" });
   

4. The syndication link http://{domain}/{directory}/syndication.axd?format={format} is mapped to my existing controller with the following route:

   routes.MapRoute(
       "MyRoute",
       "syndication.axd",
       new { controller = "MyController", action = "MyAction" });
   

The nice thing about this approach is that I can support these legacy links without any additional code, just these additions to my routing table.

Not-Found Links

Requests to the new blog engine might not return anything for a couple of reasons:

1. An invalid controller or action is specified
2. A invalid parameter is passed to a controller action

For invalid controller requests, a catch-all route is a good starting point, such as the following:

routes.MapRoute(
    "Error",
    "{*url}",
    new { controller = "Error", action = "Http404" });

This ensures that requests of an unrecognised pattern will be passed to an error controller, and an appropriate view used to render an error.

For invalid parameters, additional code is required in the relevant controllers to redirect to a "Not Found" view, for example when a requested post is not found.