How to ignore routes in ASP.NET Core? - asp.net-core

Question

Previously, one would add something like this to Global.aspx.cs, which is gone in .NET Core:
routes.IgnoreRoute("{*favicon}", new { favicon = #"(.*/)?favicon.ico(/.*)?" });
Here's what I currently have in my Startup.cs (for .NET Core):
app.UseDefaultFiles();
app.UseStaticFiles();
app.UseMvc(routes =>
{
routes.MapRoute(
name: "default",
template: "{controller=Home}/{action=Index}/{id?}");
routes.MapSpaFallbackRoute(
name: "spa-fallback",
defaults: new { controller = "Home", action = "Index" });
});
The problem is that in MVC (pre-Core) routes was a RouteCollection and in .NET Core it's a Microsoft.AspNetCore.Routing.IRouteBuilder so IgnoreRoute is not a valid method.

Answer 1

You could write middleware for this.
public void Configure(IApplciationBuilder app) {
app.UseDefaultFiles();
// Make sure your middleware is before whatever handles
// the resource currently, be it MVC, static resources, etc.
app.UseMiddleware<IgnoreRouteMiddleware>();
app.UseStaticFiles();
app.UseMvc();
}
public class IgnoreRouteMiddleware {
private readonly RequestDelegate next;
// You can inject a dependency here that gives you access
// to your ignored route configuration.
public IgnoreRouteMiddleware(RequestDelegate next) {
this.next = next;
}
public async Task Invoke(HttpContext context) {
if (context.Request.Path.HasValue &&
context.Request.Path.Value.Contains("favicon.ico")) {
context.Response.StatusCode = 404;
Console.WriteLine("Ignored!");
return;
}
await next.Invoke(context);
}
}

Answer 2

.NET Core 3.1
For .NET Core 3.1 with endpoint routing, this seems like the easiest way. You don't need to build a middleware just for this simple case.
app.UseEndpoints(endpoints =>
{
endpoints.MapGet("/favicon.ico", async (context) =>
{
context.Response.StatusCode = 404;
});
// more routing
});
The original question is about ignoring routes. If you do want to serve a favicon, you can add HTML markup in _Layout.cshtml like this. This technique allows more control over where the icon is served from.
<link rel="icon" href="#Url.Content("~/images/favicon.ico")" />
I am using both of these techniques in my code.

Answer 3

If you want to make a static file accessible without the routing condition, simply use the build-in StaticFiles Middleware.
Activate it with app.UseStaticFiles();
in Configure Method and put your static files in wwwroot directory.
They're availible on HOST/yourStaticFile
For more information, refer here

Answer 4

inside public void Configure
add
app.Map("/favicon.ico", delegate { });

Answer 5

Allow favicon requests to be parsed by the route handler, and keep your routes to a minimum. Avoid using middleware, this just adds additional complexity to your code and means all other requests must go through the middleware before the route handler, which is worse in terms of performance for busy websites. For websites that aren't busy you would just be wasting your time worrying about this.
See https://github.com/aspnet/Routing/issues/207

Answer 6

In ASP.NET Core, you can write a constrained catch-all route template. To do so, in your ASP.NET Core example, replace the call to routes.MapSpaFallbackRoute with the following:
// Returns the home/index page for unknown files, except for
// favicon.ico, in which case a 404 error is returned.
routes.MapRoute(
name: "spa-fallback",
template: "{*url:regex(^(?!favicon.ico).*$)}",
defaults: new { Controller = "Home", action = "Index" });