private async void ComboBoxBookings_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
try
{
BookingViewModel.Booking.Id = int.Parse(ComboBoxBookings.SelectedValue.ToString());
await BookingViewModel.GetABookingAsync();
}
catch (Exception ex)
{
await new MessageDialog(ex.Message).ShowAsync();
}
HandleButtonVisibility();
}