wpf - 在应用了 HierarchicalDataTemplate 的 WPF TreeView 中绑定(bind) SelectedItem

Question

我有一个数据绑定(bind)TreeView我想绑定(bind)SelectedItem . This attached behavior没有 HierarchicalDataTemplate 也能完美运行但附加的行为只能以一种方式工作(UI 到数据)而不是另一种方式，因为现在 e.NewValue是 MyViewModel不是 TreeViewItem .

这是附加行为的代码片段:

private static void OnSelectedItemChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
{
    var item = e.NewValue as TreeViewItem;
    if (item != null)
    {
        item.SetValue(TreeViewItem.IsSelectedProperty, true);
    }
}

这是我的 TreeView定义:

<Window xmlns:interactivity="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity">
    <TreeView ItemsSource="{Binding MyItems}" VirtualizingStackPanel.IsVirtualizing="True">
        <interactivity:Interaction.Behaviors>
            <behaviors:TreeViewSelectedItemBindingBehavior SelectedItem="{Binding SelectedItem, Mode=TwoWay}" />
        </interactivity:Interaction.Behaviors>
        <TreeView.Resources>
            <HierarchicalDataTemplate DataType="{x:Type local:MyViewModel}" ItemsSource="{Binding Children}">
                <TextBlock Text="{Binding Name}"/>
            </HierarchicalDataTemplate>
        </TreeView.Resources>
    </TreeView>
</Window>

如果我可以引用 TreeView在附加的行为方法 OnSelectedItemChanged ，也许我可以使用 this question 中的答案获取 TreeViewItem但我不知道怎么去那里。有谁知道如何以及这是正确的方法吗？

Answer 1

如果你像我一样发现 this answer有时会崩溃，因为 itemPresenter为空，那么对该解决方案的修改可能对您有用。

更改OnSelectedItemChanged对此(如果树尚未加载，则它会等到树被加载并再次尝试):

private static void OnSelectedItemChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
{
    Action<TreeViewItem> selectTreeViewItem = tvi2 =>
    {
        if (tvi2 != null)
        {
            tvi2.IsSelected = true;
            tvi2.Focus();
        }
    };

    var tvi = e.NewValue as TreeViewItem;

    if (tvi == null)
    {
        var tree = ((BindableTreeViewSelectedItemBehavior) sender).AssociatedObject;
        if (!tree.IsLoaded)
        {
            RoutedEventHandler handler = null;
            handler = (sender2, e2) =>
            {
                tvi = GetTreeViewItem(tree, e.NewValue);
                selectTreeViewItem(tvi);
                tree.Loaded -= handler;
            };
            tree.Loaded += handler;

            return;
        }
        tvi = GetTreeViewItem(tree, e.NewValue);
    }

    selectTreeViewItem(tvi);
}