Google OAuth Access Token Empty

Question

i think this question might be asked a Million Times but i did not find any answers out there.

I'm trying to access Google Calendar with my Unity Project, so I'm Using C# but cant use the Official google client libraries as its not supported.

Sadly Every time i try to get the Access Token from the server i get either a 404 or just a empty response.

My Code:

private static string tokenUrl = "https://oauth2.googleapis.com/";
public static string GetOAuthTokens(string auth_code, string grantType)
{
    RestClient rc = new RestClient(tokenUrl);
    RestRequest request = new RestRequest(Method.POST);
    request.Parameters.Clear();

    request.Resource = "token";
    request.AddHeader("Content-Type", "application/x-www-form-urlencoded");
    request.AddParameter("auth_code", auth_code, ParameterType.RequestBody);
    request.AddParameter("client_id", client_id, ParameterType.RequestBody);
    request.AddParameter("secret", client_secret, ParameterType.RequestBody);
    request.AddParameter("grant_type", grantType, ParameterType.RequestBody);
    request.AddParameter("redirect_uri", "http://localhost:4444", ParameterType.RequestBody);
    return rc.Execute(request).Content;
}

And i've called that method with:

 Debug.Log(OAuth2.GetOAuthTokens(code, "authorization_code"));

that Debug.Log is just for debugging.

I've seen a lot of people saying i need to whitelist my Uri but i cant find that menu point in the credentials.

Im searching for about 6 hours now. Please Help!

Answer 1

I figured it out: request.AddParameter("auth_code", auth_code, ParameterType.RequestBody);

had to be: request.AddParameter("code", auth_code, ParameterType.GetOrPost);

and i think i had to rename the Parameter keys to match the Documentation

Answer 2

I made a DLL file of Google Calendar using their .NET SDK as explained here. I modified it a little to work with Unity and then used that dll file in Unity project. It worked for me.

Below is DLL code:

  static string[] Scopes = { CalendarService.Scope.CalendarReadonly };
    static string ApplicationName = "Google Calendar API .NET Quickstart";

    public void Main()
    {
        UserCredential credential;
     
        using (var stream =
            new FileStream(UnityEngine.Application.streamingAssetsPath + "/credentials.json", FileMode.Open, FileAccess.Read))
        {
            // The file token.json stores the user's access and refresh tokens, and is created
            // automatically when the authorization flow completes for the first time.
            string credPath = "token.json";
            credential = GoogleWebAuthorizationBroker.AuthorizeAsync(
                GoogleClientSecrets.Load(stream).Secrets,
                Scopes,
                "user",
                CancellationToken.None,
                new FileDataStore(credPath, true)).Result;
            Console.WriteLine("Credential file saved to: " + credPath);
        }

        // Create Google Calendar API service.
        var service = new CalendarService(new BaseClientService.Initializer()
        {
            HttpClientInitializer = credential,
            ApplicationName = ApplicationName,
        });

        // Define parameters of request.
        EventsResource.ListRequest request = service.Events.List("primary");
        request.TimeMin = DateTime.Now;
        request.ShowDeleted = false;
        request.SingleEvents = true;
        request.MaxResults = 10;
        request.OrderBy = EventsResource.ListRequest.OrderByEnum.StartTime;

        // List events.
        Events events = request.Execute();
        Debug.Log("Upcoming events:");
        if (events.Items != null && events.Items.Count > 0)
        {
            foreach (var eventItem in events.Items)
            {
                string when = eventItem.Start.DateTime.ToString();
                if (String.IsNullOrEmpty(when))
                {
                    when = eventItem.Start.Date;
                }
                Debug.Log("Event Summery: " + eventItem.Summary + " | " + " On " + when);
            }
        }
        else
        {
            Debug.Log("No upcoming events found.");
        }
        Console.Read();

    }

On Unity Side Code:

public Calendar calendar = new Calendar();

private void Start()
{
    calendar.Main();
}

It gives me calendar event summery and date. You can download project from here.