public async void Delete(object sender, RoutedEventArgs e)
        {
            if (SaveButton.Visibility == Visibility.Visible)
            {
                SaveButton.Visibility = Visibility.Collapsed;
            }

            if (AddButton.Visibility == Visibility.Visible)
            {
                AddButton.Visibility = Visibility.Collapsed;
            }

            try
            {
                if (TextId.IsReadOnly)
                {
                    TextId.IsReadOnly = false;
                }

                await _service.Delete(SelectedAirplaneType.Id.ToString());

                // refresh listView
                AirplaneTypes.Clear();
                foreach (var airplaneType in await _service.LoadData())
                {
                    AirplaneTypes.Add(airplaneType);
                }
            }
            catch (Exception)
            {
            }
        }
        public async void LoadData(object sender, RoutedEventArgs e)
        {
            if (SaveButton.Visibility == Visibility.Visible)
            {
                SaveButton.Visibility = Visibility.Collapsed;
            }

            if (AddButton.Visibility == Visibility.Visible)
            {
                AddButton.Visibility = Visibility.Collapsed;
            }

            AirplaneTypes.Clear();
            foreach (var airplaneType in await _service.LoadData())
            {
                AirplaneTypes.Add(airplaneType);
            }
        }
        public async void Add(object sender, RoutedEventArgs e)
        {
            SelectedAirplaneType.Id               = 0;
            SelectedAirplaneType.AirplaneModel    = TextAirplaneModel.Text;
            SelectedAirplaneType.SeatsCount       = int.Parse(TextSeatsCount.Text);
            SelectedAirplaneType.CarryingCapacity = int.Parse(TextCarryingCapacity.Text);

            await _service.Create(SelectedAirplaneType);

            AddButton.Visibility = Visibility.Collapsed;
            TextId.IsReadOnly    = false;

            // refresh listView
            AirplaneTypes.Clear();
            foreach (var airplaneType in await _service.LoadData())
            {
                AirplaneTypes.Add(airplaneType);
            }
        }