public ActionResult AddAttendee(Attendee model)
        {
            if(AttendeeIsNotYetRegistered(model.PhoneNumber))
            {
                _attendeeService.AddAttendee(model);
            }

            return Json(true);
        }
 public ActionResult GetAttendee(Attendee model)
 {
     var result = Json(_attendeeService.GetAttendee(model.PhoneNumber));
     return result;
 }
 public async Task AddAttendee(Attendee attendee)
 {
     await _repository.CreateItemAsync(attendee);
 }