Handling route errors in ASP.NET MVC

Question

I understand how to set up my own routes, but how does one handle routes that fall through the cracks of the routing table? I mean, I guess the default {controller}/{action}/{id} route could be a generic catchall, but I'm not sure if that's the way to go. I like letting my users know they've requested data/a 'page' that doesn't exist.

Is this where the [HandleError] filter comes in? How does that work, exactly?

Answer 1

If your route is not found, you want to handle it as a normal HTTP 404 error.

If you only add the [HandleError] attribute to your class or action, MVC will look for an Error view in your views folder.

You could also add an ErrorController or even a static page and add this to your Web.config:

<customErrors mode="On" >
    <error statusCode="404" redirect="/Error/PageNotFound/" />
</customErrors>

Or you could handle the HTTP 404 in your Global.asax.cs and route to an ErrorController programmatically. That's how I generally do it:

protected void Application_Error(object sender, EventArgs e)
{
    var ex = Server.GetLastError().GetBaseException();

    var routeData = new RouteData();

    if (ex.GetType() == typeof(HttpException))
    {
        var httpException = (HttpException)ex;

        switch (httpException.GetHttpCode())
        {
            case 404:
                routeData.Values.Add("action", "PageNotFound");
                break;
            default:
                routeData.Values.Add("action", "GeneralError");
                break;
        }
    }
    else
    {
        routeData.Values.Add("action", "GeneralError");
    }

    routeData.Values.Add("controller", "Error");
    routeData.Values.Add("error", ex);

    IController errorController = new ErrorController();
    errorController.Execute(new RequestContext(new HttpContextWrapper(Context), routeData));
}

Answer 2

You can define a route like this:

routes.MapRoute(
                "PageNotFound",
                "{*catchall}",
                new { controller = "Home", action = "PageNotFound" }
                );

Than make an action in a controller like this:

        public ActionResult PageNotFound()
        {
            ViewBag.Message = "Sorry, the page you requested does not exist.";
            return View();
        }

This route sould be added last, that way it will catch any request that can't be mapped.

HandleError attribute is used to catch exceptions that may occure within controller actions.