public async void AddEntity(object sender, RoutedEventArgs e) { SelectedItem.Id = Guid.NewGuid(); SelectedItem.Name = TextAirplaneName.Text; SelectedItem.AirplaneType = AirplaneTypeDtos .FirstOrDefault(airplaneType => airplaneType.Model == TextAirplaneName.Text); SelectedItem.DateOfIssue = DateTime.Parse(TextDateOfIssue.Text); SelectedItem.LifeTime = TimeSpan.Parse(TextLifeTime.Text); await _airplaneService.CreateEntityAsync(SelectedItem); AddButton.Visibility = Visibility.Collapsed; TextId.IsReadOnly = false; await LoadAirplaneAsync(); }