IIS7 URL Rewrite - Add “www” prefix

Question

How to force example.com to be redirected to www.example.com with URL rewriting in IIS7? What kind of rule should go into the web.config? Thanks.

Answer 1

I'm not sure if this helps, but i opted to do this at the app level. Here's a quick action filter I wrote to do this.. Simply add the class somewhere in your project, and then you can add [RequiresWwww] to a single action or an entire controller.

public class RequiresWww : ActionFilterAttribute
    {
        public override void OnActionExecuting(ActionExecutingContext filterContext)
        {
            HttpRequestBase req = filterContext.HttpContext.Request;
            HttpResponseBase res = filterContext.HttpContext.Response;

            //IsLocal and IsLoopback i'm not too sure on the differences here, but I have both to eliminate local dev conditions. 
            if (!req.IsLocal && !req.Url.Host.StartsWith("www") && !req.Url.IsLoopback)
            {
                var builder = new UriBuilder(req.Url)
                {
                    Host = "www." + req.Url.Host
                };

                res.Redirect(builder.Uri.ToString());

            }

            base.OnActionExecuting(filterContext);
        }
    }

Then

[RequiresWwww]
public ActionResult AGreatAction()
{
...
}

or

[RequiresWwww]
public class HomeController : BaseAppController 
{
..
..
}

Hope that helps someone. Cheers!