MVC 6 Routing, SPA fallback + 404 Error Page

Question

With RC1 of ASP.NET Core 1.0's MVC 6 you can map routes from within your Startup.Configure function when invoking app.UseMvc. I have mapped a "spa-fallback" route that will ensure that the HomeController and Index view are the defaults like so:

public void Configure(IApplicationBuilder app, 
                      IHostingEnvironment env, 
                      ILoggerFactory loggerFactory)
{
    // ... omitted for brevity
    app.UseExceptionHandler("/Home/Error");
    app.UseStatusCodePagesWithRedirects("/Home/Error/{0}");

    app.UseMvc(routes =>
    {
        routes.MapRoute("default", "{controller=Home}/{action=Index}/{id?}");
        routes.MapRoute("spa-fallback", "{*anything}", new { controller = "Home", action = "Index" });
        routes.MapWebApiRoute("defaultApi", "api/{controller}/{id?}");
    });
}

I desire the fallback so that my Angular2 app's routes will not result in an HTTP Status Code of 404, Not Found. But I also need to correctly handle when a user does inadvertently attempt to navigate to a page view that doesn't exist. You might notice that I have also called app.UseStatusCodePagesWithRedirects("/Home/Error/{0}");.

The call to redirect to my error page with the status code and the "spa-fallback" route seem mutually exclusive -- meaning it appears that I can only have one or the other (but sadly not both). Does anyone know how I could manage to have the best of both worlds?

Answer 1

It took me some time to figure out how to do this without serving my index using MVC and to still receive 404s for missing files. Here's my http pipeline:

    public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
    {
        app.UseDefaultFiles();
        app.UseStaticFiles();

        app.UseMvc(                
            routes => {
                routes.MapRoute(
                    name: "api",
                    template: "api/{controller}/{action}/{id?}");

                // ## commented out since I don't want to use MVC to serve my index.    
                // routes.MapRoute(
                //     name:"spa-fallback", 
                //     template: "{*anything}", 
                //     defaults: new { controller = "Home", action = "Index" });
        });

        // ## this serves my index.html from the wwwroot folder when 
        // ## a route not containing a file extension is not handled by MVC.  
        // ## If the route contains a ".", a 404 will be returned instead.
        app.MapWhen(context => context.Response.StatusCode == 404 &&
                               !Path.HasExtension(context.Request.Path.Value),
                    branch => {
                           branch.Use((context, next) => {
                               context.Request.Path = new PathString("/index.html");
                               Console.WriteLine("Path changed to:" + context.Request.Path.Value);
                               return next();});

                    branch.UseStaticFiles();
        });            
    }