How to pass parameter to fb auth callback in ASP.NE Core 2.1, without identity?

Question

How I can to pass parameter to Challenge method, and read it after facebook callback? I want to link social accounts, and id can be user id for example.

Account controller example:

    [Route("accounts/facebook/{id}")]
    public IActionResult Facebook(string id)
    {
        var auth = new AuthenticationProperties { RedirectUri = "/accounts/facebook/callback" };

        return Challenge(auth, "Facebook");
    }

    [Route("accounts/facebook/callback")]
    public void Callback() 
    {
        //need to read custumId
    }

Startup.cs example:

 public void ConfigureServices(IServiceCollection services)
    {
        services
            .AddAuthentication()
            .AddFacebook(x =>
            {
                x.AppId = "*";
                x.AppSecret = "*";
                x.CallbackPath = "/accounts/facebook/callback";
            });

        services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
    }

    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        app.UseDeveloperExceptionPage();

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

Summary, I need to link social accounts to exiting profile in my system.

Answer 1

Very simple - you can pass needed information to query string in redirect uri