Question

我正在创建一个UWP应用程序，它应该从API获取一些数据并显示它，这种情况发生在“Refresh（）”方法上。

一切正常，直到我尝试进行搜索，即“搜索（）”方法。

从MainPage调用“Search（）”方法。

public sealed partial class MarvelMenu : Page, INotifyPropertyChanged
{
    //Backing field.
    private ObservableCollection<Character> _marvelCharacters = new ObservableCollection<Character>();

    //Property
    public ObservableCollection<Character> MarvelCharacters
    {
        get { return _marvelCharacters; }

        set
        {
            if (value != _marvelCharacters)
            {
                _marvelCharacters = value;

                //Notify of the change.
                NotifyPropertyChanged();
            }
        }
    }

    //PropertyChanged event.
    public event PropertyChangedEventHandler PropertyChanged;

    //PropertyChanged event triggering method.
    private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
    }

    private ObservableCollection<ComicBook> MarvelComics;

    public MarvelMenu()
    {
        this.InitializeComponent();
        MarvelComics = new ObservableCollection<ComicBook>();
    }

    private async void Page_Loaded(object sender, RoutedEventArgs e)
    {
        var storageFile = await StorageFile.GetFileFromApplicationUriAsync(new Uri("ms-appx:///VoiceCommandDictionary.xml"));
        await VoiceCommandDefinitionManager.InstallCommandDefinitionsFromStorageFileAsync(storageFile);
        Refresh();
    }

    public async void Refresh()
    {
        MyProgressRing.Visibility = Visibility.Visible;
        MyProgressRing.IsActive = true;
        ErrorTextBlock.Text = "";
        MarvelCharacters.Clear();

        while (MarvelCharacters.Count < 20)
        {
            Task t = MarvelFacade.PopulateMarvelCharactersAsync(MarvelCharacters);
            await t;
        }

        try
        {
            this.MasterListBox.SelectedIndex = 0;
        }

        catch (Exception)
        {
            return;
        }

        MyProgressRing.IsActive = false;
        MyProgressRing.Visibility = Visibility.Collapsed;
        ErrorTextBlock.Text = MarvelFacade.errorMessage;
        var attribute = await MarvelFacade.GetCharacterDataWrapperAsync();
        var myAttribute = attribute.attributionText;

        try
        {
            AttributeTextBlock.Text = myAttribute;
        }

        catch (Exception)
        {
            return;
        }
    }

    public async void Search(string searchedCharacter)
    {
        MyProgressRing.Visibility = Visibility.Visible;
        MyProgressRing.IsActive = true;
        ErrorTextBlock.Text = "";
        MarvelCharacters.Clear();
        Task t = MarvelFacade.PopulateMarvelCharactersByNameAsync(searchedCharacter, MarvelCharacters);
        await t;
        MyProgressRing.IsActive = false;
        MyProgressRing.Visibility = Visibility.Collapsed;
        ErrorTextBlock.Text = MarvelFacade.errorMessage;
    }

在调试模式下运行应用程序时，我发现C＃代码运行完美，实际上从API检索搜索到的数据，但是没有显示。即使我看到Visual Studio在该方法中执行了每个步骤，但实际上并没有显示它。

        <ListBox Name="MasterListBox"
                 ScrollViewer.VerticalScrollBarVisibility="Hidden"
                 ItemsSource="{x:Bind MarvelCharacters}"
                 Grid.RowSpan="3"
                 IsHitTestVisible="True"
                 SelectionChanged="MasterListBox_SelectionChanged">
            <ListBox.ItemTemplate>
                <DataTemplate x:DataType="data:Character">
                    <ListBoxItem Style="{StaticResource ListBoxItemStyle}"
                                 Margin="-12,-11,-12,-13"
                                 IsHitTestVisible="False">
                        <StackPanel Orientation="Horizontal">
                            <Ellipse Width="40"
                                     Height="40"
                                     Margin="4">
                                <Ellipse.Fill>
                                    <ImageBrush ImageSource="{x:Bind thumbnail.small}"/>
                                </Ellipse.Fill>
                            </Ellipse>
                            <TextBlock Text="{x:Bind name}"
                                       VerticalAlignment="Center"
                                       Width="180"
                                       TextTrimming="WordEllipsis"
                                       FontSize="15"
                                       Margin="10,0,0,0"/>
                        </StackPanel>
                    </ListBoxItem>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

我的ListBox绑定到“MarvelCharacters”，它是一个公共的ObservableCollection属性。所以它在应用程序启动时显示正常，但不会刷新以显示搜索结果。

任何人都可以帮助我，我真的很感激。

Answer 1

Xaml中的绑定具有称为＆＃39; Mode＆＃39;的属性。此属性定义绑定的方式。

有3种模式：OneTime，OneWay，TwoWay

OneTime ：使用将让你只将ur数据绑定到ur UI一次，这是在初始化期间。在此之后，UI是独立的。 x：Bind将默认模式设置为OneTime虽然经典绑定（{Binding}）默认设置为OneWay

OneWay ：使用此功能可确保每次数据更新时都更新UI。

{x:Bind name,Mode=OneWay}

{Binding name,Mode=OneWay}

虽然Classic绑定不需要显式声明，但您可以简单地绑定，但对于Compiled Binding，显式声明是必要的。

从MainPage.xaml.cs调用该方法时，它会运行，但UI不会更新

1 个答案: