我提出了这个解决方案(我认为这是最简单的，并且没有内存泄漏)，它非常适合从视图的选定项更新ViewModel的选定项。

请注意，从ViewModel中更改所选项不会更新视图中的所选项。

public class TreeViewEx : TreeView
{
    public static readonly DependencyProperty SelectedItemExProperty = DependencyProperty.Register("SelectedItemEx", typeof(object), typeof(TreeViewEx), new FrameworkPropertyMetadata(default(object))
    {
        BindsTwoWayByDefault = true // Required in order to avoid setting the "BindingMode" from the XAML
    });

    public object SelectedItemEx
    {
        get => GetValue(SelectedItemExProperty);
        set => SetValue(SelectedItemExProperty, value);
    }

    protected override void OnSelectedItemChanged(RoutedPropertyChangedEventArgs<object> e)
    {
        SelectedItemEx = e.NewValue;
    }
}

XAML usage

<l:TreeViewEx ItemsSource="{Binding Path=Items}" SelectedItemEx="{Binding Path=SelectedItem}" >

这可以以一种“更好”的方式完成，只使用绑定和GalaSoft MVVM Light库的EventToCommand。在您的VM中添加一个命令，当所选项目发生变化时将调用该命令，并初始化该命令以执行任何必要的操作。在这个例子中，我使用了一个RelayCommand，只设置SelectedCluster属性。

public class ViewModel
{
    public ViewModel()
    {
        SelectedClusterChanged = new RelayCommand<Cluster>( c => SelectedCluster = c );
    }

    public RelayCommand<Cluster> SelectedClusterChanged { get; private set; } 

    public Cluster SelectedCluster { get; private set; }
}

然后在xaml中添加EventToCommand行为。使用混合非常简单。

<TreeView
      x:Name="lstClusters"
      ItemsSource="{Binding Path=Model.Clusters}" 
      ItemTemplate="{StaticResource HoofdCLusterTemplate}">
    <i:Interaction.Triggers>
        <i:EventTrigger EventName="SelectedItemChanged">
            <GalaSoft_MvvmLight_Command:EventToCommand Command="{Binding SelectedClusterChanged}" CommandParameter="{Binding ElementName=lstClusters,Path=SelectedValue}"/>
        </i:EventTrigger>
    </i:Interaction.Triggers>
</TreeView>

我偶然发现了这一页，寻找与原作者相同的答案，并证明了总是有不止一种方法来做这件事，解决方案对我来说甚至比这里提供的答案更容易，所以我想我不妨添加到堆中。

绑定的动机是保持良好& MVVM。ViewModel的可能用法是有一个带有名称的属性，例如“CurrentThingy”，而在其他地方，其他东西上的DataContext被绑定到“CurrentThingy”。

而不是通过额外的步骤(例如:自定义行为，第三方控制)来支持从TreeView到我的模型的良好绑定，然后从其他东西到我的模型，我的解决方案是使用简单的元素绑定其他东西到TreeView。SelectedItem，而不是将其他东西绑定到ViewModel，从而跳过所需的额外工作。

XAML:

<TreeView x:Name="myTreeView" ItemsSource="{Binding MyThingyCollection}">
.... stuff
</TreeView>

<!-- then.. somewhere else where I want to see the currently selected TreeView item: -->

<local:MyThingyDetailsView 
       DataContext="{Binding ElementName=myTreeView, Path=SelectedItem}" />

当然，这对于读取当前选择的项目很好，但不能设置它，这是我所需要的。

我意识到这已经有一段时间了，但FWIW我正在使用Telerik的RadTreeView, SelectedItem似乎工作得很好-要么问题已经修复，要么Telerik已经为我们工作了。

还有一种方法可以在不使用Interaction.Behaviors的情况下创建XAML可绑定SelectedItem属性。

public static class BindableSelectedItemHelper
{
    #region Properties

    public static readonly DependencyProperty SelectedItemProperty = DependencyProperty.RegisterAttached("SelectedItem", typeof(object), typeof(BindableSelectedItemHelper),
        new FrameworkPropertyMetadata(null, OnSelectedItemPropertyChanged));

    public static readonly DependencyProperty AttachProperty = DependencyProperty.RegisterAttached("Attach", typeof(bool), typeof(BindableSelectedItemHelper), new PropertyMetadata(false, Attach));

    private static readonly DependencyProperty IsUpdatingProperty = DependencyProperty.RegisterAttached("IsUpdating", typeof(bool), typeof(BindableSelectedItemHelper));

    #endregion

    #region Implementation

    public static void SetAttach(DependencyObject dp, bool value)
    {
        dp.SetValue(AttachProperty, value);
    }

    public static bool GetAttach(DependencyObject dp)
    {
        return (bool)dp.GetValue(AttachProperty);
    }

    public static string GetSelectedItem(DependencyObject dp)
    {
        return (string)dp.GetValue(SelectedItemProperty);
    }

    public static void SetSelectedItem(DependencyObject dp, object value)
    {
        dp.SetValue(SelectedItemProperty, value);
    }

    private static bool GetIsUpdating(DependencyObject dp)
    {
        return (bool)dp.GetValue(IsUpdatingProperty);
    }

    private static void SetIsUpdating(DependencyObject dp, bool value)
    {
        dp.SetValue(IsUpdatingProperty, value);
    }

    private static void Attach(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        TreeListView treeListView = sender as TreeListView;
        if (treeListView != null)
        {
            if ((bool)e.OldValue)
                treeListView.SelectedItemChanged -= SelectedItemChanged;

            if ((bool)e.NewValue)
                treeListView.SelectedItemChanged += SelectedItemChanged;
        }
    }

    private static void OnSelectedItemPropertyChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        TreeListView treeListView = sender as TreeListView;
        if (treeListView != null)
        {
            treeListView.SelectedItemChanged -= SelectedItemChanged;

            if (!(bool)GetIsUpdating(treeListView))
            {
                foreach (TreeViewItem item in treeListView.Items)
                {
                    if (item == e.NewValue)
                    {
                        item.IsSelected = true;
                        break;
                    }
                    else
                       item.IsSelected = false;                        
                }
            }

            treeListView.SelectedItemChanged += SelectedItemChanged;
        }
    }

    private static void SelectedItemChanged(object sender, RoutedEventArgs e)
    {
        TreeListView treeListView = sender as TreeListView;
        if (treeListView != null)
        {
            SetIsUpdating(treeListView, true);
            SetSelectedItem(treeListView, treeListView.SelectedItem);
            SetIsUpdating(treeListView, false);
        }
    }
    #endregion
}

然后你可以在你的XAML中使用它:

<TreeView  helper:BindableSelectedItemHelper.Attach="True" 
           helper:BindableSelectedItemHelper.SelectedItem="{Binding SelectedItem, Mode=TwoWay}">

这个属性存在:TreeView。设置SelectedItem

但是它是只读的，所以你不能通过绑定来赋值它，只能检索它