c# - 从 TreeView 获取 SelectedItem？

Question

有谁知道我如何从 TreeView 中获取 SelectedItem（而不是 Header）？
这是我的代码：

<TreeView Name="treeView1" DataContext="{Binding Path=PresentationsViewModel}" Grid.Column="1" >
    <TreeViewItem IsExpanded="True" Header="Objects-A-List" DisplayMemberPath="Name" ItemsSource="{Binding Path=MyItem.ListA}"></TreeViewItem>
    <TreeViewItem IsExpanded="True" Header="Objects-B-List" DisplayMemberPath="Name" ItemsSource="{Binding Path=MyItem.ListB}"></TreeViewItem>
    <TreeViewItem IsExpanded="True" Header="Objects-C-List" DisplayMemberPath="Name" ItemsSource="{Binding Path=MyItem.ListC}"></TreeViewItem>
</TreeView>

请注意，有 3 个不同的列表，包含 3 个不同的对象类型。有这样的东西对我有很大帮助：

public Object SelectedObject
{
    set { _selectedObject = value; RunMyMethod(); RaisePropertyChanged("SelectedObject"); }
}  

Answer 1

好的，我知道这是一个老问题，可能已经死了，但查理说得对。这也可以在代码中使用。例如，您可以这样做：

<ContentPresenter Content="{Binding ElementName=treeView1, Path=SelectedItem}" />

这将显示所选项目。您可以向其中添加样式或 DataTemplate，或对您尝试显示的对象使用默认 DataTemplate。

Answer 2

步骤 1 安装 NuGet：Install-Package System.Windows.Interactivity.WPF

第 2 步 在您的 Window 标签中添加：xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"

第 3 步 在 TreeView 中添加：

    <TreeView Name="treeView1" ... >
         <i:Interaction.Triggers>
              <i:EventTrigger EventName="SelectedItemChanged">
                   <i:InvokeCommandAction Command="{Binding SelectedItemChangedCommand}" CommandParameter="{Binding ElementName=treeView1, Path=SelectedItem}"/>
              </i:EventTrigger>
          </i:Interaction.Triggers>
   ...
   </TreeView>

第 4 步 在您的 ViewModel 中添加：

        private ICommand _selectedItemChangedCommand;
        public ICommand SelectedItemChangedCommand
        {
            get
            {
                if (_selectedItemChangedCommand == null)
                    _selectedItemChangedCommand = new RelayCommand(args => SelectedItemChanged(args));
                return _selectedItemChangedCommand;
            }
        }

        private void SelectedItemChanged(object args)
        {
            //Cast your object
        }

Answer 3

Diego Torres 的回答简洁明了！但是对于那些不想为此目的安装 NuGet 包的人，您可以创建自己的依赖属性，在触发偶数时执行命令。

namespace View.Helper
{
    public class EventToCommandAdaptor
    {
        public static readonly DependencyProperty TreeViewSelectedItemChangedCommand_DpProp =
            DependencyProperty.RegisterAttached(
              "TreeViewSelectedItemChangedCommand",
              typeof(ICommand),
              typeof(EventToCommandAdaptor), // owner type
              new PropertyMetadata(new PropertyChangedCallback(AttachOrRemoveTreeViewSelectedItemChangedEvent))
              );

        public static ICommand GetTreeViewSelectedItemChangedCommand(DependencyObject obj)
        {
            return (ICommand)obj.GetValue(TreeViewSelectedItemChangedCommand_DpProp);
        }

        public static void SetTreeViewSelectedItemChangedCommand(DependencyObject obj, ICommand value)
        {
            obj.SetValue(TreeViewSelectedItemChangedCommand_DpProp, value);
        }

        public static void AttachOrRemoveTreeViewSelectedItemChangedEvent(DependencyObject obj, DependencyPropertyChangedEventArgs args)
        {
            TreeView treeview = obj as TreeView;
            if (treeview != null)
            {
                ICommand cmd = (ICommand)args.NewValue;

                if (args.OldValue == null && args.NewValue != null)
                {
                    treeview.SelectedItemChanged += ExecuteTreeViewSelectedItemChanged;
                }
                else if (args.OldValue != null && args.NewValue == null)
                {
                    treeview.SelectedItemChanged -= ExecuteTreeViewSelectedItemChanged;
                }
            }
        }

        private static void ExecuteTreeViewSelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> args)
        {
            DependencyObject obj = sender as DependencyObject;
            ICommand cmd = (ICommand)obj.GetValue(TreeViewSelectedItemChangedCommand_DpProp);

            if (cmd != null)
            {
                if (cmd.CanExecute(args.NewValue))
                {
                    cmd.Execute(args.NewValue);
                }
            }
        }
    }
}

包括xmlns:vh="clr-namespace:View.Helper"在<Windows></Windows>

TreeView 看起来像：

<TreeView ItemsSource="{Binding MyItemSource}"
    vh:EventToCommandAdaptor.TreeViewSelectedItemChangedCommand="{Binding MyCommand}">
</TreeView>

我在遇到类似情况时学会了这个技巧：我想在触发 DataGrid.MouseDoubleClick 事件时执行命令。但是很抱歉我忘了标出来源。

Answer 4

也许我误解了你的问题，但是，

treeView1.SelectedItem

应该管用。