Updated Routing With WebForms

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A while back I wrote a sample that demonstrated how to use Routing with WebForms.

If you missed it, you can *download the code** here*

With the recent announcement that Routing will be included with .NET 3.5 SP1, you can see why I wanted to put that demo together.

I have since updated that sample to work with the versions of Routing that comes with the April CodePlex build of MVC. This should also work with the SP1 Beta. I’ll verify that when I get a moment.

As part of this update, I added a new feature which allows applying a simple substitution. For example, suppose you want URLs such as /forms/whatever to route to a physical file /forms/whatever.aspx. You can do the following:

routes.Map("forms/{whatever}").To("~/forms/{whatever}.aspx");

One mistake a lot of people make when looking at URL Routing is to think of it as URL Rewriting. The difference is subtle, but important. There is no URL rewriting going on with Routing.

What happens here is when an incoming request URL matches this route (aka the URL pattern on the left), the WebFormRouteHandler will instantiate the physical ASPX Page specified in the virtual path on the right and use that http handler to handle the request (Recall that the Page class implements the IHttpHandler interface). As far as the page is concerned, the URL is /forms/whatever/. For example, this means that the URL rendered by your form will match the current URL, unlike what typically happens with URL rewriting.

This is why the above won’t work if you try to map a route to a virtual path that contains a query string:

//WRONG!!!
routes.Map("forms/{whatever}").To("~/{whatever}.aspx?what={whatever}");

The reason the above route won’t work is that the virtual path on the right isn’t valid. The path needs to specify a page we can instantiate, not a request for an URL.

To save you from having to visit the previous post, here is a link to download the code

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