Learn Net Core 2.0 make a blog error page middleware

Customerrorpagesmiddleware

 Public classCustomerrorpagesmiddleware {Private ReadOnlyrequestdelegate _next; Private ReadOnlyMicrosoft.Extensions.Logging.ILogger _logger; Private ReadOnlyihostingenvironment _env;  PublicCustomerrorpagesmiddleware (requestdelegate Next, Iloggerfactory loggerfactory, Ihos Tingenvironment env) {_next=Next; _logger= loggerfactory.createlogger<customerrorpagesmiddleware>(); _env=env; }         Public AsyncTask Invoke (HttpContext context) {Try            {                await_next (context); }            Catch(Exception ex) {_logger. LogError (0, ex,"An unhandled exception have occurred while executing the request"); if(context. response.hasstarted) {_logger. Logwarning ("The response has already started, the error page middleware would not be executed."); Throw; }                Try{context.                    Response.Clear (); Context. Response.statuscode= -; return; }                Catch(Exception ex2) {_logger. LogError (0, EX2,"An exception is thrown attempting to display the error page."); }                Throw; }            finally            {                varStatusCode =context.                Response.statuscode; if(StatusCode = =404|| StatusCode = = -|| StatusCode = =403)                {                                      awaitErrorpage.responseasync (context.                Response, statuscode,_env); }                            }        }    }

ErrorPage

  Public Static classErrorPage { Public Static AsyncTask Responseasync (HttpResponse response,intStatusCode, Ihostingenvironment env) {            if(StatusCode = =404)            {                                  awaitResponse.                       WriteAsync (Page404,encoding.utf8); }            Else if(StatusCode = = -)            {                awaitResponse.            WriteAsync (Page500); }Else if(StatusCode = =403{ //No permissions server will return 403;                 awaitResponse. WriteAsync (Page403); }        }        Private Static stringPage404 ="404"; Private Static stringPage500 =""; Private Static stringPage403 ="403"; }

Customerrorpagesextensions

 Public Static class customerrorpagesextensions    {        publicstatic iapplicationbuilder usecustomerrorpages ( This Iapplicationbuilder app)            {ifnull)            {                throw New ArgumentNullException (nameof (APP));            }             return app. Usemiddleware<customerrorpagesmiddleware>();        }    }

Startup

App. Usecustomerrorpages ();

Learn Net Core 2.0 make a blog error page middleware