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>
走吧
．.． 是一个更好的答案，但没有提到一种在ViewModel中获取/设置SelectedItem的方法。
添加一个IsSelected布尔属性到ItemViewModel，并在TreeViewItem的样式设置器中绑定到它。
在ViewModel中添加SelectedItem属性，作为TreeView的DataContext。这是上面解决方案中缺少的部分。
' ItemVM...
Public Property IsSelected As Boolean
Get
Return _func.SelectedNode Is Me
End Get
Set(value As Boolean)
If IsSelected value Then
_func.SelectedNode = If(value, Me, Nothing)
End If
RaisePropertyChange()
End Set
End Property
' TreeVM...
Public Property SelectedItem As ItemVM
Get
Return _selectedItem
End Get
Set(value As ItemVM)
If _selectedItem Is value Then
Return
End If
Dim prev = _selectedItem
_selectedItem = value
If prev IsNot Nothing Then
prev.IsSelected = False
End If
If _selectedItem IsNot Nothing Then
_selectedItem.IsSelected = True
End If
End Set
End Property
<TreeView ItemsSource="{Binding Path=TreeVM}"
BorderBrush="Transparent">
<TreeView.ItemContainerStyle>
<Style TargetType="TreeViewItem">
<Setter Property="IsExpanded" Value="{Binding IsExpanded}"/>
<Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}"/>
</Style>
</TreeView.ItemContainerStyle>
<TreeView.ItemTemplate>
<HierarchicalDataTemplate ItemsSource="{Binding Children}">
<TextBlock Text="{Binding Name}"/>
</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
</TreeView>
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。
我试过了这道题的所有解。没有人能完全解决我的问题。所以我认为最好使用这样的继承类与重定义属性SelectedItem。如果你从GUI中选择tree element并在代码中设置此属性值，它将完美地工作
public class TreeViewEx : TreeView
{
public TreeViewEx()
{
this.SelectedItemChanged += new RoutedPropertyChangedEventHandler<object>(TreeViewEx_SelectedItemChanged);
}
void TreeViewEx_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
{
this.SelectedItem = e.NewValue;
}
#region SelectedItem
/// <summary>
/// Gets or Sets the SelectedItem possible Value of the TreeViewItem object.
/// </summary>
public new object SelectedItem
{
get { return this.GetValue(TreeViewEx.SelectedItemProperty); }
set { this.SetValue(TreeViewEx.SelectedItemProperty, value); }
}
// Using a DependencyProperty as the backing store for MyProperty. This enables animation, styling, binding, etc...
public new static readonly DependencyProperty SelectedItemProperty =
DependencyProperty.Register("SelectedItem", typeof(object), typeof(TreeViewEx),
new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, SelectedItemProperty_Changed));
static void SelectedItemProperty_Changed(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e)
{
TreeViewEx targetObject = dependencyObject as TreeViewEx;
if (targetObject != null)
{
TreeViewItem tvi = targetObject.FindItemNode(targetObject.SelectedItem) as TreeViewItem;
if (tvi != null)
tvi.IsSelected = true;
}
}
#endregion SelectedItem
public TreeViewItem FindItemNode(object item)
{
TreeViewItem node = null;
foreach (object data in this.Items)
{
node = this.ItemContainerGenerator.ContainerFromItem(data) as TreeViewItem;
if (node != null)
{
if (data == item)
break;
node = FindItemNodeInChildren(node, item);
if (node != null)
break;
}
}
return node;
}
protected TreeViewItem FindItemNodeInChildren(TreeViewItem parent, object item)
{
TreeViewItem node = null;
bool isExpanded = parent.IsExpanded;
if (!isExpanded) //Can't find child container unless the parent node is Expanded once
{
parent.IsExpanded = true;
parent.UpdateLayout();
}
foreach (object data in parent.Items)
{
node = parent.ItemContainerGenerator.ContainerFromItem(data) as TreeViewItem;
if (data == item && node != null)
break;
node = FindItemNodeInChildren(node, item);
if (node != null)
break;
}
if (node == null && parent.IsExpanded != isExpanded)
parent.IsExpanded = isExpanded;
if (node != null)
parent.IsExpanded = true;
return node;
}
}
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。
