Use specific status code error page in area | Asp.net core - asp.net-core

Question

I manage status codes error using
app.UseStatusCodePagesWithRedirects("/StatusCodeError/{0}");
But when an error occurs in the area, the page is redirected out of the area and shows the general error page.
How do I make sure that an area-specific error page is displayed if an error occurs in the area?

Answer 1

There is no extensibility point to modify the behavior of app.UseStatusCodePagesWithRedirects, the location is formatted internally using string.Format and with only one argument passed in the placeholder {0} for the status code. So at the calling time (passing in the location format), we have no understanding about the area which is a route value available only in the context of a request processing. So you can refer to the source for StatusCodePagesExtensions and can see that UseStatusCodePagesWithRedirects just depends on an overload of the extension method StatusCodePagesExtensions.UseStatusCodePages, you can freely copy the code and modify it to make another version of UseStatusCodePagesWithRedirects that accepts a location format which supports some arguments from the route values.
Here I've made a simple one for you:
public static class StatusCodePagesApplicationBuilderExtensions
{
public static IApplicationBuilder UseStatusCodePagesWithRouteDataAndRedirects(this IApplicationBuilder app, string locationFormat)
{
if (app == null)
{
throw new ArgumentNullException(nameof(app));
}
var shouldPrependPathBase = locationFormat.StartsWith("~");
locationFormat = shouldPrependPathBase ? locationFormat.Substring(1) : locationFormat;
return app.UseStatusCodePages(context =>
{
//here is the point we can evaluate for the actual location
//by replacing the placeholders with route value
var location = Regex.Replace(locationFormat, #"\{[^}]+\}", m => {
//ignore the placeholder for status code
if (m.Value == "{0}") return m.Value;
var routeKey = m.Value.Trim('{', '}');
var routeValue = context.HttpContext.GetRouteValue(routeKey);
return routeValue?.ToString();
});
location = string.Format(CultureInfo.InvariantCulture, location, context.HttpContext.Response.StatusCode);
location = (shouldPrependPathBase ? context.HttpContext.Request.PathBase : PathString.Empty) + location;
context.HttpContext.Response.Redirect(location);
return Task.CompletedTask;
});
}
}
Now you can include any route data in the location format, in your case you just need the area, so the code will be like this:
app.UseStatusCodePagesWithRouteDataAndRedirects("/{area}/StatusCodeError/{0}");
NOTE: be careful with redirecting, you may encounter an error saying something like too many redirects, that's because of redirecting to a URL which in return causes a loop of redirects.