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

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。

其他回答

我给你带来了我的解决方案,它具有以下特点:

支持2种绑定方式 自动更新TreeViewItemIsSelected属性(根据SelectedItem) 没有TreeView子类 绑定到ViewModel的项可以是任何类型(甚至是null)

1/在你的CS中粘贴以下代码:

public class BindableSelectedItem
{
    public static readonly DependencyProperty SelectedItemProperty = DependencyProperty.RegisterAttached(
        "SelectedItem", typeof(object), typeof(BindableSelectedItem), new PropertyMetadata(default(object), OnSelectedItemPropertyChangedCallback));

    private static void OnSelectedItemPropertyChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var treeView = d as TreeView;
        if (treeView != null)
        {
            BrowseTreeViewItems(treeView, tvi =>
            {
                tvi.IsSelected = tvi.DataContext == e.NewValue;
            });
        }
        else
        {
            throw new Exception("Attached property supports only TreeView");
        }
    }

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

    public static object GetSelectedItem(DependencyObject element)
    {
        return element.GetValue(SelectedItemProperty);
    }

    public static void BrowseTreeViewItems(TreeView treeView, Action<TreeViewItem> onBrowsedTreeViewItem)
    {
        var collectionsToVisit = new System.Collections.Generic.List<Tuple<ItemContainerGenerator, ItemCollection>> { new Tuple<ItemContainerGenerator, ItemCollection>(treeView.ItemContainerGenerator, treeView.Items) };
        var collectionIndex = 0;
        while (collectionIndex < collectionsToVisit.Count)
        {
            var itemContainerGenerator = collectionsToVisit[collectionIndex].Item1;
            var itemCollection = collectionsToVisit[collectionIndex].Item2;
            for (var i = 0; i < itemCollection.Count; i++)
            {
                var tvi = itemContainerGenerator.ContainerFromIndex(i) as TreeViewItem;
                if (tvi == null)
                {
                    continue;
                }

                if (tvi.ItemContainerGenerator.Status == System.Windows.Controls.Primitives.GeneratorStatus.ContainersGenerated)
                {
                    collectionsToVisit.Add(new Tuple<ItemContainerGenerator, ItemCollection>(tvi.ItemContainerGenerator, tvi.Items));
                }

                onBrowsedTreeViewItem(tvi);
            }

            collectionIndex++;
        }
    }

}

2/在XAML文件中使用的例子

<TreeView myNS:BindableSelectedItem.SelectedItem="{Binding Path=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}" />    

我找到了一个解决办法。它可以移动混乱,这样MVVM就可以工作了。

首先添加这个类:

public class ExtendedTreeView : TreeView
{
    public ExtendedTreeView()
        : base()
    {
        this.SelectedItemChanged += new RoutedPropertyChangedEventHandler<object>(___ICH);
    }

    void ___ICH(object sender, RoutedPropertyChangedEventArgs<object> e)
    {
        if (SelectedItem != null)
        {
            SetValue(SelectedItem_Property, SelectedItem);
        }
    }

    public object SelectedItem_
    {
        get { return (object)GetValue(SelectedItem_Property); }
        set { SetValue(SelectedItem_Property, value); }
    }
    public static readonly DependencyProperty SelectedItem_Property = DependencyProperty.Register("SelectedItem_", typeof(object), typeof(ExtendedTreeView), new UIPropertyMetadata(null));
}

并添加到你的xaml:

 <local:ExtendedTreeView ItemsSource="{Binding Items}" SelectedItem_="{Binding Item, Mode=TwoWay}">
 .....
 </local:ExtendedTreeView>

一切都很复杂……使用Caliburn Micro (http://caliburnmicro.codeplex.com/)

观点:

<TreeView Micro:Message.Attach="[Event SelectedItemChanged] = [Action SetSelectedItem($this.SelectedItem)]" />

ViewModel:

public void SetSelectedItem(YourNodeViewModel item) {}; 

当点击某些项目列表时,你会在“选定”属性中获得数据。 视图模型:

public class ShellViewModel : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    protected void NotifyPropertyChanged(String info)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(info));
        }
    }

    private ObservableCollection<Books> _books;

    private List<Books> bookList = new List<Books>();

    public ObservableCollection<Books> Books
    {
        get { return _books; }
        set { _books = value; NotifyPropertyChanged("Books"); }
    }

    private Books books;

    public Books Selected
    {
        get { return books; }
        set { books = value; }
    }


    public ShellViewModel()
    {
        bookList = new List<Books>()
        {
            new Books{BookName = "Harry Poter",Price ="15$"},
            new Books{BookName = "Harry Poter 2 ",Price ="14.95$"},
            new Books{BookName = "Harry Poter 3",Price ="18.50$"},
            new Books{BookName = "Harry Poter 4",Price ="32.90$"},
        };

        Books = new ObservableCollection<Books>(bookList);
    }
}

public class Books
{
    public string BookName { get; set; }
    public string Price { get; set; }
}

XAML:

 <ListView x:Name="lst" Grid.Row="2" ItemsSource="{Binding Books}" SelectedItem="{Binding Selected}">
        <ListView.View>
            <GridView >
                <GridViewColumn Header="Name" DisplayMemberBinding="{Binding BookName}"  />
                <GridViewColumn Header="Price" Width="100" DisplayMemberBinding="{Binding Price}"/>
            </GridView>
        </ListView.View>
    </ListView>