Servicestack Display 404 page CatchAllHandlers - servicestack

Question

Im using servicestack Core with kestrel. I made a CatchAllHandlers delegate with the following code.
var requestType = typeof(NotFoundPage);
var restPath = new RestPath(requestType, pathInfo);
return new RestHandler { RestPath = restPath, RequestName = restPath.RequestType.GetOperationName(), ResponseContentType = contentType };
But the problem is that my ServicestackApi now is no longer reachable, url: /json/reply/GetApiCall goes to the 404 not found page.
Is there a way to solve this? can i check if its an api call or can i go later in the pipeline to handle the request?
update
I found that if i remove CatchAllHandler and just add the next middleware this middleware is called:
app.Use((context, next) =>
{
context.Response.Body.Write("yaayaya");
return Task.CompletedTask;
});
But this is not what i want, i want to stay inside the servicestack request.
update 2
Looking at the source-code i find HttpHandlerFactory has a property NotFoundHttpHandler Which is filled from the AppHost.
CustomErrorHttpHandlers.Add(HttpStatusCode.NotFound, new PageNotFoundHandler());
The only downside is that i can't provide any request specific information to this Urlhandler, such as the url itself:
public class PageNotFoundHandler : RestHandler
{
public PageNotFoundHandler()
{
var restPath = new RestPath(typeof(Error404), "/Url/For?");
}
}
Trying to make this work but i'm getting stuck on that my RestHandler has different amount of components than the url since this PageNotFoundHandler is made before the RestHandler.
But Basically what im looking for is to Handle a different service/InputDto
I've tried RequestConverters but this code is not reached when CatchAllHandlers doesn't return an Handler. so im stuck in this space in the middle. Anyway i could make all the left over routes, route to a single Dto?

Answer 1

.NET Core's new pipeline programming model expects you to call the next middleware if it wasn't already handled by any of the previously registered middleware which is how .NET Core lets you combine multiple different middlewares into the same App.
Handling Not Found Requests with the last Middleware
The last middleware that's registered will be able to handle any unhandled requests so for instance if you wanted to return a static image for unhandled requests you could register middleware after ServiceStack, e.g:
app.UseServiceStack(new AppHost());
app.Use(new StaticFileHandler("wwwroot/img/404.png"));
Or if you wanted to return a custom 404 page instead:
app.Use(new RazorHandler("/404"));
Which will render the /wwwroot/404.cshtml Razor View with ServiceStack's MVC Razor Views.
This would be the preferred way to handle Not Found requests in .NET Core in which you will be able to register additional middleware after ServiceStack to handle non-ServiceStack requests.
Calling a ServiceStack Service for unhandled requests
If you wanted to call a ServiceStack Service for any unhandled requests you can use a Fallback Route which matches on any request, e.g:
[FallbackRoute("/{Path*}")]
public class Error404
{
public string Path { get; set; }
}
public class UnhandledRequestService : Service
{
public object Any(Error404 request) => ...;
}