如何检索在WPF-treeview中选择的项?我想在XAML中这样做,因为我想绑定它。

您可能认为它是SelectedItem,但显然它不存在是只读的,因此不可用。

这就是我想做的:

<TreeView ItemsSource="{Binding Path=Model.Clusters}" 
            ItemTemplate="{StaticResource ClusterTemplate}"
            SelectedItem="{Binding Path=Model.SelectedCluster}" />

我想将SelectedItem绑定到我的Model上的一个属性。

但这给了我一个错误:

“SelectedItem”属性是只读的,不能从标记中设置。

编辑: 这就是我解决这个问题的方法:

<TreeView
          ItemsSource="{Binding Path=Model.Clusters}" 
          ItemTemplate="{StaticResource HoofdCLusterTemplate}"
          SelectedItemChanged="TreeView_OnSelectedItemChanged" />

在我的xaml的代码背后文件:

private void TreeView_OnSelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
{
    Model.SelectedCluster = (Cluster)e.NewValue;
}

当前回答

在学习了一天的互联网后,我找到了自己的解决方案,在一个普通的WPF/ c#环境中创建一个普通的树视图后选择一个项目

private void BuildSortTree(int sel)
        {
            MergeSort.Items.Clear();
            TreeViewItem itTemp = new TreeViewItem();
            itTemp.Header = SortList[0];
            MergeSort.Items.Add(itTemp);
            TreeViewItem prev;
            itTemp.IsExpanded = true;
            if (0 == sel) itTemp.IsSelected= true;
            prev = itTemp;
            for(int i = 1; i<SortList.Count; i++)
            {

                TreeViewItem itTempNEW = new TreeViewItem();
                itTempNEW.Header = SortList[i];
                prev.Items.Add(itTempNEW);
                itTempNEW.IsExpanded = true;
                if (i == sel) itTempNEW.IsSelected = true;
                prev = itTempNEW ;
            }
        }

其他回答

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

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}">

也可以使用TreeView项的IsSelected属性来完成。我是这么做的,

public delegate void TreeviewItemSelectedHandler(TreeViewItem item);
public class TreeViewItem
{      
  public static event TreeviewItemSelectedHandler OnItemSelected = delegate { };
  public bool IsSelected 
  {
    get { return isSelected; }
    set 
    { 
      isSelected = value;
      if (value)
        OnItemSelected(this);
    }
  }
}

然后在包含TreeView绑定到的数据的ViewModel中,只需订阅TreeViewItem类中的事件。

TreeViewItem.OnItemSelected += TreeViewItemSelected;

最后,在同一个ViewModel中实现这个处理器,

private void TreeViewItemSelected(TreeViewItem item)
{
  //Do something
}

当然,绑定,

<Setter Property="IsSelected" Value="{Binding IsSelected}" />    

我建议对Steve Greatrex提供的行为进行补充。他的行为并不反映来自源的更改,因为它可能不是TreeViewItems的集合。 所以这是一个在树中找到TreeViewItem的问题,它的数据上下文是来自源的selectedValue。 TreeView有一个名为“ItemsHost”的受保护属性,它包含TreeViewItem集合。我们可以通过反射获得它,并遍历树搜索所选项目。

private static void OnSelectedItemChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        var behavior = sender as BindableSelectedItemBehaviour;

        if (behavior == null) return;

        var tree = behavior.AssociatedObject;

        if (tree == null) return;

        if (e.NewValue == null) 
            foreach (var item in tree.Items.OfType<TreeViewItem>())
                item.SetValue(TreeViewItem.IsSelectedProperty, false);

        var treeViewItem = e.NewValue as TreeViewItem; 
        if (treeViewItem != null)
        {
            treeViewItem.SetValue(TreeViewItem.IsSelectedProperty, true);
        }
        else
        {
            var itemsHostProperty = tree.GetType().GetProperty("ItemsHost", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);

            if (itemsHostProperty == null) return;

            var itemsHost = itemsHostProperty.GetValue(tree, null) as Panel;

            if (itemsHost == null) return;

            foreach (var item in itemsHost.Children.OfType<TreeViewItem>())
                if (WalkTreeViewItem(item, e.NewValue)) break;
        }
    }

    public static bool WalkTreeViewItem(TreeViewItem treeViewItem, object selectedValue) {
        if (treeViewItem.DataContext == selectedValue)
        {
            treeViewItem.SetValue(TreeViewItem.IsSelectedProperty, true);
            treeViewItem.Focus();
            return true;
        }

        foreach (var item in treeViewItem.Items.OfType<TreeViewItem>())
            if (WalkTreeViewItem(item, selectedValue)) return true;

        return false;
    }

这种方式的行为适用于双向绑定。或者,也可以将ItemsHost获取移动到Behavior的OnAttached方法,从而节省每次绑定更新时使用反射的开销。

我知道这个帖子已经10年了,但问题仍然存在....

最初的问题是“检索”所选项目。我还需要在我的视图模型中“获取”选定的项目(而不是设置它)。在这个线程中的所有答案中,“Wes”的答案是唯一一个以不同的方式解决问题的答案:如果你可以使用“Selected Item”作为数据绑定的目标,那么就使用它作为数据绑定的源。Wes对另一个视图属性做过,我将对viewmodel属性做

我们需要两样东西:

在视图模型中创建一个依赖属性(在我的情况下,类型为'MyObject',因为我的树视图绑定到'MyObject'类型的对象) 从Treeview绑定。SelectedItem属性在视图的构造函数中(是的,这是后面的代码,但很可能你也会init你的datacontext)

Viewmodel:

public static readonly DependencyProperty SelectedTreeViewItemProperty = DependencyProperty.Register("SelectedTreeViewItem", typeof(MyObject), typeof(MyViewModel), new PropertyMetadata(OnSelectedTreeViewItemChanged));

    private static void OnSelectedTreeViewItemChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        (d as MyViewModel).OnSelectedTreeViewItemChanged(e);
    }

    private void OnSelectedTreeViewItemChanged(DependencyPropertyChangedEventArgs e)
    {
        //do your stuff here
    }

    public MyObject SelectedWorkOrderTreeViewItem
    {
        get { return (MyObject)GetValue(SelectedTreeViewItemProperty); }
        set { SetValue(SelectedTreeViewItemProperty, value); }
    }

构造函数:

Binding binding = new Binding("SelectedItem")
        {
            Source = treeView, //name of tree view in xaml
            Mode = BindingMode.OneWay
        };

        BindingOperations.SetBinding(DataContext, MyViewModel.SelectedTreeViewItemProperty, binding);