Creating multilingual not found page in MVC

Question

We have a multilingual website that has content in four languages.Every language is understood by the language name that we add at the first of our url. This is our routeConfig.cs:

   routes.MapRoute(
            name: "Default",
            url: "{lang}/{controller}/{action}/{id}/{title}",
            defaults: new { lang = "fa", controller = "Home", action = "Index", id = UrlParameter.Optional,title = UrlParameter.Optional }

and this is generated the url: /en/ContactUs/Index

Also, in our controllers we get the language name from url and change the currentCulture and currentUiCulture based on it. Now, we want to have a not found page in all of the languages. Normally, to make it happen we add an error contoller and a NotFound action and view, then we add this section in our web.config:

  <customErrors mode="On" defaultRedirect="error">
  <error statusCode="404" redirect="error/notfound" />
  <error statusCode="403" redirect="error/forbidden" />
</customErrors>

We have added a NotFound page that we use .resx files in it to make rtl/ltr and to show the messages in four languages. But the problem here is that in a multilingual website we are not allowed to use this address "error/notfound" because there is no languagename in it and we don't know how to add the language name in redirect="error/notfound" in the web.config file to create something like "en/error/notfound" or "fa/error/notfound". every help would be highly appreciated

Answer 1

First of all, have a look at this answer for info about localizing your site via URL.

Next, <customErrors> is a catch-all for ASP.NET error messages. But in general, you have control over a 404 (routing miss) within ASP.NET MVC by using a catch-all route. In this case, you can simply localize the catch-all route and get rid of this configuration in web.config.

public class RouteConfig
{
    public static void RegisterRoutes(RouteCollection routes)
    {
        routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

        routes.MapRoute(
            name: "Localized-Default",
            url: "{lang}/{controller}/{action}/{id}",
            defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional },
            constraints: new { lang = new CultureConstraint(defaultCulture: "fa", pattern: "[a-z]{2}") }
        );

        routes.MapRoute(
            name: "Default",
            url: "{controller}/{action}/{id}",
            defaults: new { lang = "fa", controller = "Home", action = "Index", id = UrlParameter.Optional }
        );

        // Catch-all route (for routing misses)
        routes.MapRoute(
            name: "Localized-404",
            url: "{lang}/{*url}",
            defaults: new { controller = "Error", action = "PageNotFound" },
            constraints: new { lang = new CultureConstraint(defaultCulture: "fa", pattern: "[a-z]{2}") }
        );

        routes.MapRoute(
            name: "Default-404",
            url: "{*url}",
            defaults: new { lang = "fa", controller = "Error", action = "PageNotFound" }
        );
    }
}

ErrorController

public class ErrorController : Controller
{
    public ActionResult PageNotFound()
    {
        Response.CacheControl = "no-cache";
        Response.StatusCode = (int)HttpStatusCode.NotFound;

        return View();
    }
}

That takes care of the route misses within ASP.NET. For those that don't hit ASP.NET (assuming you are hosting using IIS), you should use the <httpErrors> section of web.config rather than <customErrors>. <httpErrors> is localizable via the prefixLanguageFilePath setting.

Optional string attribute.

Specifies the initial path segment when generating the path for a custom error. This segment appears before the language-specific portion of the custom error path. For example, in the path C:\Inetpub\Custerr\en-us\404.htm, C:\Inetpub\Custerr is the prefixLanguageFilePath.

<configuration>
   <system.webServer>
      <httpErrors errorMode="DetailedLocalOnly" defaultResponseMode="File" >
         <remove statusCode="404" />
         <error statusCode="404"
            prefixLanguageFilePath="C:\Contoso\Content\errors"
            path="404.htm" />
       </httpErrors>
   </system.webServer>
</configuration>

Which means you would need to set up a file structure with language prefix, and use static files as targets.

C:\Contoso\Content\errors\fa\404.htm
C:\Contoso\Content\errors\en\404.htm

AFAIK, this unfortunately means you need to have physical files at these locations. However, you could have the content of these pages setup to do both a meta-refresh redirect and a JavaScript redirect to the correct controller action.

<html>
<head>
    <title>404 Not Found</title>
    <meta http-equiv="refresh" content="1;http://www.example.com/fa/Error/PageNotFound" />
</head>
<body>
    <!-- Add localized message (for those browsers that don't redirect). -->
    
    <script>
        //<!--
        setTimeout(function () {
            window.location = "http://www.example.com/fa/Error/PageNotFound";
        }, 1000);
        //-->
    </script>
</body>
</html>

Answer 2

The customErrors section in web.config is the static data about some status-code and how they will be handled. The responsibility of this section can be generated dynamically by the Application_EndRequest method in Global.asax.

protected void Application_EndRequest()
{
    if (Context.Response.StatusCode == 404)
    {
        Response.Clear();

        var routeData = new RouteData();
        HttpContextBase currentContext = new HttpContextWrapper(HttpContext.Current);
        var lang = RouteTable.Routes.GetRouteData(currentContext).Values["lang"];
        routeData.Values["lang"] = lang;
        routeData.Values["controller"] = "CustomError";
        routeData.Values["action"] = "NotFound";

        IController customErrorController = new CustomErrorController();
        customErrorController.Execute(new RequestContext(new HttpContextWrapper(Context), routeData));
    }
}