Google Calendar API for UWP Windows 10 Application One or more errors occurred

Question

I\'m trying to use Google Calendar API v3, but i have problems while running the codes, it always gives me that error :

An exception of type \'System

Answer 1

The Google API Client Library for .NET does not support UWP by now. So we can't use Google.Apis.Calendar.v3 Client Library in UWP apps now. For more info, please see the similar question: Universal Windows Platform App with google calendar.

To use Google Calendar API in UWP, we can call it through REST API. To use the REST API, we need to authorize requests first. For how to authorize requests, please see Authorizing Requests to the Google Calendar API and Using OAuth 2.0 for Mobile and Desktop Applications.

After we have the access token, we can call Calendar API like following:

var clientId = "{Your Client Id}";
var redirectURI = "pw.oauth2:/oauth2redirect";
var scope = "https://www.googleapis.com/auth/calendar.readonly";
var SpotifyUrl = $"https://accounts.google.com/o/oauth2/auth?client_id={clientId}&redirect_uri={Uri.EscapeDataString(redirectURI)}&response_type=code&scope={Uri.EscapeDataString(scope)}";
var StartUri = new Uri(SpotifyUrl);
var EndUri = new Uri(redirectURI);

// Get Authorization code
WebAuthenticationResult WebAuthenticationResult = await WebAuthenticationBroker.AuthenticateAsync(WebAuthenticationOptions.None, StartUri, EndUri);
if (WebAuthenticationResult.ResponseStatus == WebAuthenticationStatus.Success)
{
    var decoder = new WwwFormUrlDecoder(new Uri(WebAuthenticationResult.ResponseData).Query);
    if (decoder[0].Name != "code")
    {
        System.Diagnostics.Debug.WriteLine($"OAuth authorization error: {decoder.GetFirstValueByName("error")}.");
        return;
    }

    var autorizationCode = decoder.GetFirstValueByName("code");


    //Get Access Token
    var pairs = new Dictionary();
    pairs.Add("code", autorizationCode);
    pairs.Add("client_id", clientId);
    pairs.Add("redirect_uri", redirectURI);
    pairs.Add("grant_type", "authorization_code");

    var formContent = new Windows.Web.Http.HttpFormUrlEncodedContent(pairs);

    var client = new Windows.Web.Http.HttpClient();
    var httpResponseMessage = await client.PostAsync(new Uri("https://www.googleapis.com/oauth2/v4/token"), formContent);
    if (!httpResponseMessage.IsSuccessStatusCode)
    {
        System.Diagnostics.Debug.WriteLine($"OAuth authorization error: {httpResponseMessage.StatusCode}.");
        return;
    }

    string jsonString = await httpResponseMessage.Content.ReadAsStringAsync();
    var jsonObject = Windows.Data.Json.JsonObject.Parse(jsonString);
    var accessToken = jsonObject["access_token"].GetString();


    //Call Google Calendar API
    using (var httpRequest = new Windows.Web.Http.HttpRequestMessage())
    {
        string calendarAPI = "https://www.googleapis.com/calendar/v3/users/me/calendarList";

        httpRequest.Method = Windows.Web.Http.HttpMethod.Get;
        httpRequest.RequestUri = new Uri(calendarAPI);
        httpRequest.Headers.Authorization = new Windows.Web.Http.Headers.HttpCredentialsHeaderValue("Bearer", accessToken);

        var response = await client.SendRequestAsync(httpRequest);

        if (response.IsSuccessStatusCode)
        {
            var listString = await response.Content.ReadAsStringAsync();
            //TODO
        }
    }
}