Using Xamarin Essentials WebAuthenticator to get Google Id_token

Question

Im using the Xamarin Essentials as a part of a Xamarin Forms application i'm developing. I have integrated it in to my aspnet.core backend, and it works fine.

However im getting an accesstoken returned when i sign in with google and facebook, but in case of the google login, i need the id_token and not the accesstoken.

I've looked at the 'AddJwtBearer' method on the 'AddAuthentication' part in startup, but i have not been able to make it work when i use the 'AuthenticateAsync' method in controller.

How would one accomplish this? The backend is based on code from this sample: https://github.com/xamarin/Essentials/blob/develop/Samples/Sample.Server.WebAuthenticator/Controllers/MobileAuthController.cs

Answer 1

try to get it from here:

var auth = await Request.HttpContext.AuthenticateAsync(scheme);
var idtoken = auth.Properties.GetTokenValue("id_token");

or

 string refreshToken = await HttpContext.GetTokenAsync("id_token"); 

Check this class

 public class WebAuth
    {
        private const string AuthenticationUrl ="https://myapp.com/mobileauth/";

        private string _accessToken = "";
        private bool _isAuthenticated = false;

        public string AuthToken
        {
            get => _accessToken;
            set => SetProperty(ref _accessToken, value);
        }
    
       

        async Task OnAuthenticate(string scheme)
        {
            try
            {
                scheme = "Facebook";
                WebAuthenticatorResult result = null;

                var authUrl = new Uri(AuthenticationUrl + scheme);
                var callbackUrl = new Uri("myapp://");
                result = await WebAuthenticator.AuthenticateAsync(authUrl, callbackUrl);
                
                AuthToken = string.Empty;

                if (result.Properties.TryGetValue("name", out var name) && !string.IsNullOrEmpty(name))
                {
                    AuthToken += $"Name: {name}{Environment.NewLine}";
                }

                if (result.Properties.TryGetValue("email", out var email) && !string.IsNullOrEmpty(email))
                {
                    AuthToken += $"Email: {email}{Environment.NewLine}";
                }
                
                AuthToken += result?.AccessToken ?? result?.IdToken;
                IsAuthenticated = true;
            }
            catch (Exception ex)
            {
                AuthToken = string.Empty;
            }
        }
    }