Deleting an event from Google Calendar

Question

I want to delete an event of a user's Google Calendar by using his email ID I tried the following code to delete the event.

CalendarService service = new CalendarService();
                            string calendarId = "primary";
                            service.Events.Delete(calendarId, eventId).Execute();

But it gives me following exception

Google.Apis.Requests.RequestError
Login Required [401]
Errors [
    Message[Login Required] Location[Authorization - header] Reason[required] Domain[global]
]

How do I achieve that and avoid the exception?

Answer 1

You cant just create an empty calendar service object it needs to be authenticated first.

var service = new CalendarService(new BaseClientService.Initializer()
            {
                HttpClientInitializer = credential,
                ApplicationName = "Calendar Oauth2 Authentication Sample"
            });

Your going to have to create credentials using Oauth2 in order to access the users calendar.

 /// <summary>
    /// This method requests Authentcation from a user using Oauth2.  
    /// Credentials are stored in System.Environment.SpecialFolder.Personal
    /// Documentation https://developers.google.com/accounts/docs/OAuth2
    /// </summary>
    /// <param name="clientSecretJson">Path to the client secret json file from Google Developers console.</param>
    /// <param name="userName">Identifying string for the user who is being authentcated.</param>
    /// <returns>DriveService used to make requests against the Drive API</returns>
    public static CalendarService AuthenticateOauth(string clientSecretJson, string userName)
    {
        try
        {
            if (string.IsNullOrEmpty(userName))
                throw new ArgumentNullException("userName");
            if (string.IsNullOrEmpty(clientSecretJson))
                throw new ArgumentNullException("clientSecretJson");
            if (!File.Exists(clientSecretJson))
                throw new Exception("clientSecretJson file does not exist.");

            // These are the scopes of permissions you need. It is best to request only what you need and not all of them
            string[] scopes = new string[] { CalendarService.Scope.CalendarReadonly,    //View your calendars
                                             CalendarService.Scope.Calendar};           //Manage your calendars
            UserCredential credential;
            using (var stream = new FileStream(clientSecretJson, FileMode.Open, FileAccess.Read))
            {
                string credPath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal);
                credPath = Path.Combine(credPath, ".credentials/", System.Reflection.Assembly.GetExecutingAssembly().GetName().Name);

                // Requesting Authentication or loading previously stored authentication for userName
                credential = GoogleWebAuthorizationBroker.AuthorizeAsync(GoogleClientSecrets.Load(stream).Secrets,
                                                                         scopes,
                                                                         userName,
                                                                         CancellationToken.None,
                                                                         new FileDataStore(credPath, true)).Result;
            }

            // Create Drive API service.
            return new CalendarService(new BaseClientService.Initializer()
            {
                HttpClientInitializer = credential,
                ApplicationName = "Calendar Oauth2 Authentication Sample"
            });
        }
        catch (Exception ex)
        {
            Console.WriteLine("Create Oauth2 account CalendarService failed" + ex.Message);
            throw new Exception("CreateServiceAccountCalendarFailed", ex);
        }
    }

Code ripped from my Google Calendar API sample project on github there is more code there in case you need it.