MVC Core 3.0 options.LoginPath - add localization route parameter

Question

I have the following code inside Startup - ConfigureServices:

services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme)
                .AddCookie(options =>
                {

                    options.LoginPath = new PathString("/en/Authentication/LogIn");
                });

Everything works great, but I cannot find a way to make LoginPath being localisable using URL parameter (en/de/es etc.)

My MapControllerRoute looks like:

"{lang}/{controller=Home}/{action=Index}/{id?}"

Is it possible to redirect to appropriate lang for authentication like if user was accessing /de/NeedAuth/Index - it should be redirected to /de/Authentication/LogIn ?

Answer 1

Ok. I spent an hour and here is a solution - in case anyone would have similar use case.

Step 1: Creating a new class that would dynamically get current http requests to determine redirection:

public class CustomCookieAuthenticationEvents : CookieAuthenticationEvents
    {
        public override Task RedirectToLogin(RedirectContext<CookieAuthenticationOptions> context)
        {
            var httpContext = context.HttpContext;

            var routePrefix = httpContext.GetRouteValue("lang");

            context.RedirectUri = $"/{routePrefix.ToString()}/Authentication/LogIn";
            return base.RedirectToLogin(context);
        }
    }

Step 2: In Startup modifying cookie authentication declaration that relates to redirecting to authentication page:

services.AddScoped<CustomCookieAuthenticationEvents>();
            services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme)
                .AddCookie(options =>
                {
                    options.LoginPath = new PathString("/Authentication/LogIn");
                    options.EventsType = typeof(CustomCookieAuthenticationEvents);
                });

Pay attention to registering CustomCookieAuthenticationEvents as service above.