c# - 当不将子节点添加到vm的构造函数中时，WPF TreeView 不显示子节点

Question

WPF树 View 有一个奇怪的问题。在我的 View 模型中，我正在这样做:

private ObservableCollection<ITreeItem> _Tree = new ObservableCollection<ITreeItem>();
public ObservableCollection<ITreeItem> Tree
{
    get { return this._Tree; }
}

现在，当我在viewmodel的构造函数中添加一些虚拟的Parent/child数据时，如下所示:

var parent = new ParentItem(1, "test", "test2");
this.Tree.Add(parent);
for (int i = 0; i < 10; i++)
{
    parent.Childs.Add(new Child { Name= "test", Description= "test2" });
}
parent.IsExpanded = true;

树显示正确。

但是，一旦我通过方法(使用调度程序)添加了一些子项，它们根本就不会显示。例如，当我调用此方法时，仅显示根节点。

public void Update()
{
    DispatcherSingleton.Instance.CurrentDispatcher.BeginInvoke(DispatcherPriority.Normal, 
        new Action(delegate
        {
            var parent = new ParentItem(1, "test", "test2");
            this.Tree.Add(parent);
            for (int i = 0; i < 10; i++)
            {
                parent.Childs.Add(new Child { Name= "test", Description= "test2" });
            }
            parent.IsExpanded = true;
        })
    );
}

这是树 View 的XAML

<ResourceDictionary>
    <Style TargetType="TreeViewItem" x:Key="itmContStyle">
        <Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}" />
    </Style>
    <Style TargetType="{x:Type TreeViewItem}">
        <Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}" />
        <Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}" />
    </Style>
    <HierarchicalDataTemplate x:Key="hDataTemplate"  ItemsSource="{Binding Childs}">
        <StackPanel Orientation="Horizontal">
            <Image Source="{Binding Image, Mode=TwoWay}" Margin="1" />
            <Image x:Name="currentImage" Source="/WpfApp;component/Resources/Images/ac.png" Visibility="Collapsed"></Image>
            <TextBlock Text="{Binding SortOrder}" Margin="1" />
            <TextBlock Text="." Margin="0,1,1,0" />
            <TextBlock Text="{Binding Bezeichnung}" Margin="1" />
        </StackPanel>
        <HierarchicalDataTemplate.Triggers>
            <DataTrigger Binding="{Binding RelativeSource={RelativeSource AncestorType=TreeViewItem}, Path=IsSelected}" Value="True">
                <Setter TargetName="currentImage" Property="Visibility" Value="Visible"/>
            </DataTrigger>
        </HierarchicalDataTemplate.Triggers>
    </HierarchicalDataTemplate>
</ResourceDictionary>

...

<TreeView  HorizontalAlignment="Stretch"  VerticalAlignment="Top" 
           BorderThickness="0" 
           ItemsSource="{Binding Tree}"            
           ItemContainerStyle="{StaticResource itmContStyle}" ItemTemplate="{StaticResource hDataTemplate}">
</TreeView>

Answer 1

您似乎混淆了命名。在您的代码中，显示以下行:

parent.Childs.Add(new Child { Name= "test", Description= "test2" });

这使我认为您的数据类型具有 Childs属性。但是，在您的XAML中，您有以下内容:

<HierarchicalDataTemplate x:Key="hDataTemplate"  ItemsSource="{Binding ChildSteps}">
    ...
</HierarchicalDataTemplate>

我猜其中之一是错误的。因此，请尝试以下XAML:

<HierarchicalDataTemplate x:Key="hDataTemplate"  ItemsSource="{Binding Childs}">
    ...
</HierarchicalDataTemplate>