如何在Silverlight Treeview中选择一个项目？

Question

我有问题在Silverlight中的TreeView中选择第一个TreeViewItem。以下代码只是在方法SelectFistItemInCatTreeView中给出了一个空值。为什么？有任何想法吗？

<controls:TreeView x:Name="treeCategories" Grid.Column="1" Grid.Row="2" SelectedItemChanged="treeCategories_SelectedItemChanged"> 
    <controls:TreeView.ItemTemplate> 
    <common:HierarchicalDataTemplate ItemsSource="{Binding SubCats}"> 
     <StackPanel > 
     <TextBlock Text="{Binding Name}"></TextBlock> 
     </StackPanel> 
    </common:HierarchicalDataTemplate> 
    </controls:TreeView.ItemTemplate> 
</controls:TreeView> 



1   public MainPage() 
2   { 
3    InitializeComponent(); 
4  
5    DBService.DocTrackingServeceClient webService = new DockTracking.DBService.DocTrackingServeceClient(); 
6    webService.GetDocCategoriesCompleted += new EventHandler(webService_GetDocCategoriesCompleted); 
7    webService.GetDocCategoriesAsync(); 
8    treeCategories.Loaded += new RoutedEventHandler(treeCategories_Loaded); 
9   } 
10 
11   void webService_GetDocCategoriesCompleted(object sender, DockTracking.DBService.GetDocCategoriesCompletedEventArgs e) 
12   { 
13 
14    List cats = new List(); 
15    cats = GetCats(e.Result.ToList(), null); 
16    treeCategories.ItemsSource = cats; 
17   } 
18 
19   void treeCategories_Loaded(object sender, RoutedEventArgs e) 
20   { 
21    SelectFistItemInCatTreeView(); 
22   } 
23 
24   private void SelectFistItemInCatTreeView() 
25   { 
26    TreeViewItem item = treeCategories.ItemContainerGenerator.ContainerFromItem(treeCategories.Items[0]) as TreeViewItem; 
27    if (item != null) 
28    { 
29     item.IsSelected = true; 
30    } 
31   } 

Answer 1

调用UpdateLayout请（）来获得树型视图之前诀窍：

private void SelectFistItemInCatTreeView() 
{ 

    treeCategories.UpdateLayout(); 

    TreeViewItem item = treeCategories.ItemContainerGenerator.ContainerFromItem(treeCategories.Items[0]) as TreeViewItem; 
    if (item != null) 
    { 
    item.IsSelected = true; 
    } 
} 

Answer 2

它看起来像ContainerFromItem方法应该是通过你结合实际的项目，而不仅仅是一个tv.Items [0]。

我想看看以下内容：

• 发表贾斯汀 - 约瑟夫 - 天使约using the ContainerFromItem方法
• 上一页SO质疑有关selecting a TreeViewItem in code

Answer 3

如果您有分层数据，则只有在选择顶层的项目时才能使用。 要选择顶层下面的子项目，必须展开并遍历树，直到已创建所需项目的TreeViewItem。

See this page for TreeViewExtended

他TreeViewExtended类有一个方法叫SetSelectedItem实际工作！