In this short tutorial i’ll try to show you how to route webrequests to your generic handlers. This topic seems to be a little untouched on msdn, which is weird, because it’s very important to rewrite for example the url of images that you use on your website.
So instead of rendering html like http://yourcoolwebsite.com/imagehandler.ashx?id=10 in your image’s source tag you’ll want to have something like http://yoursweetwebsite.com/awesome.jpg .
.NET Routing allows you to do this very easily (it’s true!).
Here’s what you’ll want to do:
- create a class that implements the IHttpHandler interface
- create a class that implements the IRouteHandler interface
- do the inner plumbing (i’ll get to it don’t worry)
- reference your url format in the global.asax
- excelsior!
So instead of using an .ashx file we’ll just create an ordinary class:
.net routing to generic handler: the classes
So what we have here is both an httphandler class and the routehandler.
As you can see you can pretty much just copy the processrequest from your old generic handler to the new processrequest method of the httphandler.
The RouteHandler will basicly supply the needed request context to our HttpHandler, this is where we’ll get the parameter from; the id for example of the image to return. In the Generic Handler of old we used to get the value of the querystring from the httpcontext, this is ofcourse useless now because we need the value from our Route context.
Here’s where the publicly defined RequestContext comes in to play. As the request to the routehandler is being made we return our very own HttpHandler but first set the RequestContext. Now you’ll have all your Routing variables available within your HttpHandler.
As for the Global.asax you’ll want to add something like this :
routing to the httphandler in your global asax
As you can see, all requests that comply to this sort of route will be routed to our – very geekalicious – routehandler.
The ImageUrl can now be completed something like this: AvatarImage.ImageUrl = string.Format(“~/avatars/{0}-{1}.jpg”, “somename”, “someuniqueidentifiermaybe”);
So as usual, hope this helps someone! And i’ll be glad to hear about any mistakes or stupid thing i’ve said.
