Я настроил привязку ListView, следуя этому примеру, привязка к наблюдаемой коллекции, но когда я запускаю приложение, значения коллекции не отображаются в ListView.
Окно вывода не выдает никаких ошибок привязки, поэтому не уверен, в чем может быть ошибка привязки. Также я установил точку останова в списке перед его отправкой на вторую виртуальную машину, и он заполнен, т. е. не равен нулю.
Я предполагаю, что список во второй виртуальной машине равен нулю, поскольку он не инициализируется должным образом после передачи.
Может ли кто-нибудь посоветовать, как отладить пустой ListView?
Это привязка, установленная в представлении:
<ListBox ItemsSource="{Binding AddedSubjectGradePairsCopy}" Height="400" Margin="0,0,0,-329" VerticalAlignment="Top">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock>
<Run Text="{Binding Subject}" /><Run Text=" - " /><Run Text="{Binding Points}" />
</TextBlock>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
Контекст данных для представления устанавливается следующим образом в коде:
namespace LC_Points.View
{
/// <summary>
/// An empty page that can be used on its own or navigated to within a Frame.
/// </summary>
public sealed partial class ViewSubjectGradePage : Page
{
private NavigationHelper navigationHelper;
private ViewSubjectGradeViewModel ViewModel;
public ViewSubjectGradePage()
{
this.InitializeComponent();
this.navigationHelper = new NavigationHelper(this);
this.navigationHelper.LoadState += this.NavigationHelper_LoadState;
this.navigationHelper.SaveState += this.NavigationHelper_SaveState;
ViewModel = new ViewSubjectGradeViewModel();
this.DataContext = ViewModel;
}
/// <summary>
/// Gets the <see cref="NavigationHelper"/> associated with this <see cref="Page"/>.
/// </summary>
public NavigationHelper NavigationHelper
{
get { return this.navigationHelper; }
}
/// <summary>
/// Populates the page with content passed during navigation. Any saved state is also
/// provided when recreating a page from a prior session.
/// </summary>
/// <param name="sender">
/// The source of the event; typically <see cref="NavigationHelper"/>
/// </param>
/// <param name="e">Event data that provides both the navigation parameter passed to
/// <see cref="Frame.Navigate(Type, Object)"/> when this page was initially requested and
/// a dictionary of state preserved by this page during an earlier
/// session. The state will be null the first time a page is visited.</param>
private void NavigationHelper_LoadState(object sender, LoadStateEventArgs e)
{
}
/// <summary>
/// Preserves state associated with this page in case the application is suspended or the
/// page is discarded from the navigation cache. Values must conform to the serialization
/// requirements of <see cref="SuspensionManager.SessionState"/>.
/// </summary>
/// <param name="sender">The source of the event; typically <see cref="NavigationHelper"/></param>
/// <param name="e">Event data that provides an empty dictionary to be populated with
/// serializable state.</param>
private void NavigationHelper_SaveState(object sender, SaveStateEventArgs e)
{
}
#region NavigationHelper registration
/// <summary>
/// The methods provided in this section are simply used to allow
/// NavigationHelper to respond to the page's navigation methods.
/// <para>
/// Page specific logic should be placed in event handlers for the
/// <see cref="NavigationHelper.LoadState"/>
/// and <see cref="NavigationHelper.SaveState"/>.
/// The navigation parameter is available in the LoadState method
/// in addition to page state preserved during an earlier session.
/// </para>
/// </summary>
/// <param name="e">Provides data for navigation methods and event
/// handlers that cannot cancel the navigation request.</param>
protected override void OnNavigatedTo(NavigationEventArgs e)
{
this.navigationHelper.OnNavigatedTo(e);
}
protected override void OnNavigatedFrom(NavigationEventArgs e)
{
this.navigationHelper.OnNavigatedFrom(e);
}
#endregion
}
}
И получение списка в ViewSubjectGradeVM через конструктор:
namespace LC_Points.ViewModel
{
public class ViewSubjectGradeViewModel
{
public ViewSubjectGradeViewModel()
{
}
/// <summary>
/// Initializes a new instance of the ViewSubjectGradeViewModel class.
/// </summary>
public ViewSubjectGradeViewModel(IEnumerable<ScoreModel> addedSubjectGradePairs)
{
this.AddedSubjectGradePairsCopy = addedSubjectGradePairs;
}
//Property for collection passed from MainViewModel
public IEnumerable<ScoreModel> AddedSubjectGradePairsCopy { get; set; }
}
}
И это модель поддержки для списка, передаваемого из MainVM в ViewSubjectGradeVM:
namespace LC_Points.Model
{
public class ScoreModel : INotifyPropertyChanged
{
// The name of the subject.
public string Subject { get; set; }
// The points paired with each grade type.
public int Points { get; set; }
public event PropertyChangedEventHandler PropertyChanged;
private void RaisePropertyChanged(string propertyName)
{
if (this.PropertyChanged != null)
{
this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
}
}
DataContext
? - person Hamlet Hakobyan   schedule 24.05.2015AddedSubjectGradePairsCopy
равно нулю. - person Hamlet Hakobyan   schedule 24.05.2015ViewModel = new ViewSubjectGradeViewModel(GetScoreModels()); this.DataContext = ViewModel;
вместоViewModel = new ViewSubjectGradeViewModel(); this.DataContext = ViewModel;
- person Hamlet Hakobyan   schedule 24.05.2015