I have an asp.net core 6.0 app with:

• WeatherForecastController
• index.html in wwwroot folder.

I have configured index.htmlas file fallback. This is themain method of program.cs;

public static void Main(string[] args)
{
    var builder = WebApplication.CreateBuilder(args);
    builder.Services.AddControllers();
    var app = builder.Build();

    // Configure the HTTP request pipeline.

    app.UseHttpsRedirection();
    app.UseAuthorization();
    app.MapControllers();
    app.UseStaticFiles();
    app.MapFallbackToFile("index.html");
    app.Run();
}

I wanted to return 404 when the path starts with /api and there is no matching controller action.

I tried adding a middleware after app.MapControllersbut the middleware executes before the controller gets called and the app always returns 404 when trying to call the API.

public static void Main(string[] args)
{
    var builder = WebApplication.CreateBuilder(args);
    builder.Services.AddControllers();
    var app = builder.Build();

    // Configure the HTTP request pipeline.

    app.UseHttpsRedirection();
    app.UseAuthorization();
    app.MapControllers();
    app.UseApiNotFound();
    app.UseStaticFiles();
    app.MapFallbackToFile("index.html");
    app.Run();
}

This is the middleware:

public class ApiNotFoundMiddleware
{

    private readonly RequestDelegate next;
    public ApiNotFoundMiddleware(RequestDelegate next)
    {
        this.next = next;
    }

    private static PathString prefix = "/api";

    public Task InvokeAsync(HttpContext context)
    {
        if (context.Request.Path.StartsWithSegments(prefix))
        {
            context.Response.StatusCode = (int)HttpStatusCode.NotFound;
            return Task.CompletedTask;
        }
        else
        {
            return this.next(context);
        }
    }
}

So

How to return 404 if path starts with '/api', there is no matching controller action and there is a file mapped as fallback?

or

is there a way to restrict fallback file to paths that do not start with /api

CodePudding user response：

You can use a different IApplicationBuilder for different conditions in your Progam.cs or Startup.cs:

e.g.:

app.MapWhen(ctx => !ctx.Request.Path.StartsWithSegments("/api"), appBuilder =>
{
    appBuilder.UseRouting();
    appBuilder.UseEndpoints(ep =>
    {
        ep.MapFallbackToFile("index.html");
    });
});

CodePudding user response：

if you add app.UseMiddleware<ApiNotFoundMiddleware>(); here like so :

app.UseHttpsRedirection();
app.UseMiddleware<ApiNotFoundMiddleware>();
app.UseAuthorization();

This returns 404 if you try navigate to anything with /api

Would this be what you're trying to achieve?