How to a I redirect to Custom Error Handler Page - asp.net-core

Question

I want a generic error page for all application errors.
I have followed the guidelines to create a custom error handler in ASP.NET core and this catches the errors as expected. However, I cannot see how to redirect to a generic error handling the page. Examples seemed to be focused on Web API, not UI.
I have the following custom error handling code
private static Task HandleExceptionAsync(HttpContext context, Exception exception)
{
context.Response.StatusCode = (int)HttpStatusCode.InternalServerError;
int exceptionId = ExceptionManager.Publish(exception);
return context.Response.WriteAsync(new ErrorViewModel()
{
ExceptionId = exceptionId
}.ToString());
}
The exception details are logged to a database and return an Id. I have a controller action that displays the Id so the users can report it.
How do I redirect to my error view?

Answer 1

In Startup.cs method you need to call ExceptionHandlerMiddleware like below.
app.UseMiddleware(typeof(ExceptionHandlerMiddleware));
create a middleware class and write below code
public class ExceptionHandlerMiddleware
{
private readonly RequestDelegate next;
public ExceptionHandlerMiddleware(RequestDelegate next)
{
this.next = next;
}
public async Task Invoke(HttpContext context)
{
try
{
//Write you logic
}
catch (Exception ex)
{
await HandleExceptionAsync(context, ex);
}
}
private static async Task HandleExceptionAsync(HttpContext context, Exception exception)
{
context.Response.StatusCode = 500;
if (IsRequestAPI(context))
{
//when request api
context.Response.ContentType = "application/json";
await context.Response.WriteAsync(JsonConvert.SerializeObject(new
{
State = 500,
message = exception.Message
}));
}
else
{
//when request page
context.Response.Redirect("/Home/Errorpage");
}
}
}
Middleware is "waterfalled" down through until either all have been executed, or one stops execution (in the case of our exception handling, we'll be writing ours so it stops the execution. More on that later).
The first things passed to your middleware is a request delegate. This is a delegate that takes the current HttpContext object and executes it. Your middleware saves this off upon creation and uses it in the Invoke() step.
Invoke() is where the work is done. Whatever you want to do to the request/response as part of your middleware is done here. Some other usages for middleware might be to authorize a request based on a header or inject a header into the request or response. For more examples, check out the Middleware documentation.