title: ASP.Net MVC:How to rewrite url by middleware in ASP.NET Core
body: <p>In asp.net 4.0 we can use work with the http module to rewrite module like so:</p>
  
  <pre><code>protected void Application_BeginRequest(Object sender, EventArgs e)
  {
      string CountryCodeInUrl = "", redirectUrl="";
      var countryCode = CookieSettings.ReadCookie();
      if (countryCode=="")
      {
          countryCode = "gb";
      }
  
      if (HttpContext.Current.Request.RawUrl.Length &gt;= 2)
      {
          CountryCodeInUrl = HttpContext.Current.Request.RawUrl.Substring(1, 2);
      }
  
      if (countryCode != CountryCodeInUrl)
      {
          if (HttpContext.Current.Request.RawUrl.Length &gt;= 2)
          {
              if (HttpContext.Current.Request.RawUrl.Substring(1, 2) != "")
              {
                  countryCode = HttpContext.Current.Request.RawUrl.Substring(1, 2);
              }
          }
          if(!System.Web.HttpContext.Current.Request.RawUrl.Contains(countryCode))
          {
              redirectUrl = string.Format("/{0}{1}", countryCode, System.Web.HttpContext.Current.Request.RawUrl);
          }
          else
          {
              redirectUrl = System.Web.HttpContext.Current.Request.RawUrl;
          }
          CookieSettings.SaveCookie(countryCode);
          System.Web.HttpContext.Current.Response.RedirectPermanent(redirectUrl);
      }   
  }
  </code></pre>
  
  <p>How could I rewrite the code above using middleware in ASP.NET Core?</p>
  
  <p>I have just partially read this article:
  <a href="https://docs.microsoft.com/en-us/aspnet/core/migration/http-modules" rel="nofollow noreferrer">https://docs.microsoft.com/en-us/aspnet/core/migration/http-modules</a></p>