MVC Custom Routing only for GET requests

Question

I have a custom routing class which I added to the RouteConfig

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

        routes.Add(new CustomRouting());

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

The CustomRouting class looks like this:

public class CustomRouting : RouteBase
{
    public override RouteData GetRouteData(HttpContextBase httpContext)
    {
        var requestUrl = httpContext.Request?.Url;
        if (requestUrl != null && requestUrl.LocalPath.StartsWith("/custom"))
        {
            if (httpContext.Request?.HttpMethod != "GET")
            {
                // CustomRouting should handle GET requests only
                return null; 
            }

            // Custom rules
            // ...
        }
        return null;
    }
}

Essentially I want to process requests that go to the /custom/* path with my custom rules.

But: Requests that are not "GET", should not be processed with my custom rules. Instead, I want to remove the /custom segment at the beginning of the path and then let MVC continue with the rest of the routing configured in RouteConfig.

How can I achieve that?

score 2 · Accepted Answer · answered Feb 15 '17 at 16:00

You can start by filtering "custom" prefixed requests in an HttpModule

HTTP Handlers and HTTP Modules Overview

Example :

public class CustomRouteHttpModule : IHttpModule
{
    private const string customPrefix = "/custom";

    public void Init(HttpApplication context)
    {
        context.BeginRequest += BeginRequest;
    }

    private void BeginRequest(object sender, EventArgs e)
    {
        HttpContext context = ((HttpApplication)sender).Context;
        if (context.Request.RawUrl.ToLower().StartsWith(customPrefix)
        && string.Compare(context.Request.HttpMethod, "GET", true) == 0)
        {
            var urlWithoutCustom = context.Request.RawUrl.Substring(customPrefix.Length);
            context.RewritePath(urlWithoutCustom);
        }
    }

    public void Dispose()
    {
    }
}

Then you can have your routes for "custom" urls

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

Note: Don't forget to register your HttpModule in your web.config

<system.webServer>
  <modules>
    <add type="MvcApplication.Modules.CustomRouteHttpModule" name="CustomRouteModule" />
  </modules>
</system.webServer>

MVC Custom Routing only for GET requests

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