How can i rewrite urls with .json to .ashx using ASP.NET handlers

Question

I have changed the architecture of my ASP.Net application, I have a lot of links that refer to .json files that are now served from .ashx files. To maintain backward compatibility and to avoid changing the existing links I have tried to use an ASP.Net handler to rename the incoming http requests.

I have tried many solutions that I found on Stackoverflow but I cannot get it to work:

public bool IsReusable
{
    get { return false; }
}

public void ProcessRequest(HttpContext context)
{
    context.Response.ContentType = "text/json";

    string newUrl = context.Request.RawUrl.Replace(".json", ".ashx");
    context.Server.Transfer(newUrl);

}

Answer 1

have a look at URL Rewriting Middleware in ASP.NET Core and ASP.NET Core URL Rewriting

You can use the URL Rewriting middleware to rewrite the urls similar to this startup.cs :

using System;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Rewrite;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Net.Http.Headers;

namespace WebApplication1
{
    public class Startup
    {
        // This method gets called by the runtime. Use this method to add services to the container.
        // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
        public void ConfigureServices(IServiceCollection services)
        {
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            var options = new RewriteOptions()
                .Add(RedirectJsonFileRequests);
            app.UseRewriter(options);

            app.Run(async (context) =>
            {
                await context.Response.WriteAsync("Hello World!");
            });
        }

        /// <summary>
        /// Redirect all requests to .json extension files to .ashx extensions, copy across the query string, if any
        /// </summary>
        /// <param name="context"></param>
        public static void RedirectJsonFileRequests(RewriteContext context)
        {
            var request = context.HttpContext.Request;

            // Because the client is redirecting back to the same app, stop 
            // processing if the request has already been redirected.
            if (request.Path.Value.EndsWith(".ashx", StringComparison.OrdinalIgnoreCase))
            {
                return;
            }

            if (request.Path.Value.EndsWith(".json", StringComparison.OrdinalIgnoreCase))
            {
                var response = context.HttpContext.Response;
                response.StatusCode = StatusCodes.Status301MovedPermanently;
                context.Result = RuleResult.EndResponse;
                response.Headers[HeaderNames.Location] =
                    request.Path.Value.Replace(".json", ".ashx", StringComparison.OrdinalIgnoreCase) + request.QueryString;
            }
        }
    }
}