如何将用户重定向到错误页面并在.NET Core的日志文件中记录错误

Question

I am working on a .NET core web app and my requirement is to handle the errors globally.

So to achieve this behavior I tried to use build in middleware UseExceptionHandler along with ExceptionHandlerOptions .

Startup.cs

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler(new ExceptionHandlerOptions {
                    ExceptionHandlingPath = "/Home/Error",
                    ExceptionHandler = async (context) => {
                        var exceptionFeature = context.Features.Get<IExceptionHandlerFeature>();
                        if (exceptionFeature != null)
                        {
                            Log.Error(exceptionFeature.Error, exceptionFeature.Error.Message);
                        }
                    }
                });
            }
     }

Above code log the errors in the log file but never redirect the user to an error page. When I remove ExceptionHandler function it works fine and redirects the user to the error page. Correct me if I missed something.

I am expecting user should redirect to error page when any unhandled exception occurs and logs the error in log file.

My workaround for this problem:

Startup.cs

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
            }
        }

HomeController.cs

public async Task<IActionResult> Error(string errorId)
        {
            var exceptionFeature = HttpContext.Features.Get<IExceptionHandlerFeature>();
            if (exceptionFeature != null)
            {
                Log.Error(exceptionFeature.Error, exceptionFeature.Error.Message);
            }
       }

Above solution works for me but is it good practice to log global error in controller? Any lead would be appriciated.

Thanks!

Answer 1

The two properties are mutually exclusive, ExceptionHandlingPath = "/Home/Error", ExceptionHandler ie, either one of those will be applied, and that's why the redirection is not happening in home/error. If you will remove the exceptionHandler, it will work for you, however you will need to do logging in the controller, which is part of the 2nd implementation you did, and there is no harm in logging it that way till this controller/action does the handling for everything.

when i say everything, it means, there are 401 errors, 404 errors, which will not be handled by the current approach, and for that you should use statusCode base approach.

the better approach will be that you Have multiple implementation of error pages: 1. 404 : where route don't exists 2. 500 : Application error (all the cases) 3 401 : if there is some kind of authorization involved.

.net core provides a lot of error handling mechanism (including the Globalfilterattributes for exception handling). However if you have a public facing application, you should target to show friendly error page to user and log rest.

You can read about it here