.NET Core C#

Google Drive Refresh Access Token

Demonstrates how to automatically refresh the access token when it expires. .NET Core C#

bool success = false;

success = true;

// It requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// This example uses a previously obtained access token having permission for the 
// Google Drive scope.

// The access token (and refresh token) was previously saved to a JSON file with this format:
// See Get Google Drive OAuth2 Access Token

// {
//   "access_token": "ya29.Gls-BsdxTWuenChv ... yzVIrXikkLxu5T6dy4I6GjADFardoz4Lruw",
//   "expires_in": 3600,
//   "refresh_token": "1/tMBJ ... 27D-Hk6rpQYBA",
//   "scope": "https://www.googleapis.com/auth/drive",
//   "token_type": "Bearer"
// }

Chilkat.JsonObject json = new Chilkat.JsonObject();
string tokenFilePath = "qa_data/tokens/googleDrive.json";
json.LoadFile(tokenFilePath);

Chilkat.OAuth2 oauth2 = new Chilkat.OAuth2();
oauth2.AccessToken = json.StringOf("access_token");
oauth2.RefreshToken = json.StringOf("refresh_token");

Chilkat.Rest rest = new Chilkat.Rest();

// Connect using TLS.
bool bAutoReconnect = true;
success = rest.Connect("www.googleapis.com",443,true,bAutoReconnect);

// Provide the authentication credentials (i.e. the access token)
rest.SetAuthOAuth2(oauth2);

// We'll test with a simple request to empty trash.
// If our access token expired, we'll get a 401 response..
string jsonResponse = rest.FullRequestNoBody("DELETE","/drive/v3/files/trash");
if (rest.LastMethodSuccess != true) {
    Debug.WriteLine(rest.LastErrorText);
    return;
}

// If the access token expired, we'll get a 401 response status with this response body:
// {
//  "error": {
//   "errors": [
//    {
//     "domain": "global",
//     "reason": "authError",
//     "message": "Invalid Credentials",
//     "locationType": "header",
//     "location": "Authorization"
//    }
//   ],
//   "code": 401,
//   "message": "Invalid Credentials"
//  }
// }
if (rest.ResponseStatusCode == 401) {

    Debug.WriteLine("Refreshing access token...");

    oauth2.AuthorizationEndpoint = "https://accounts.google.com/o/oauth2/v2/auth";
    oauth2.TokenEndpoint = "https://www.googleapis.com/oauth2/v4/token";

    //  Replace these with actual values.
    oauth2.ClientId = "GOOGLE-CLIENT-ID";
    oauth2.ClientSecret = "GOOGLE-CLIENT-SECRET";
    oauth2.Scope = "https://www.googleapis.com/auth/drive";

    // Use OAuth2 to refresh the access token.
    success = oauth2.RefreshAccessToken();
    if (success != true) {
        Debug.WriteLine(oauth2.LastErrorText);
        return;
    }

    // Save the new access token to our XML file (so we can refresh it again when needed).
    json.UpdateString("access_token",oauth2.AccessToken);

    Chilkat.FileAccess fac = new Chilkat.FileAccess();
    fac.WriteEntireTextFile(tokenFilePath,json.Emit(),"utf-8",false);

    Debug.WriteLine("Access Token Refreshed!");

    // Retry the request with the new access token..
    jsonResponse = rest.FullRequestNoBody("DELETE","/drive/v3/files/trash");
    if (rest.LastMethodSuccess != true) {
        Debug.WriteLine(rest.LastErrorText);
        return;
    }

}

// A successful response will have a status code equal to 204 and the response body is empty.
// (If not successful, then there should be a JSON response body with information..)
if (rest.ResponseStatusCode != 204) {
    Debug.WriteLine("response status code = " + Convert.ToString(rest.ResponseStatusCode));
    Debug.WriteLine("response status text = " + rest.ResponseStatusText);
    Debug.WriteLine("response header: " + rest.ResponseHeader);
    Debug.WriteLine("response JSON: " + jsonResponse);
    return;
}

Debug.WriteLine("Trash Emptied!");