TreeView中，无法以TreeviewItem的方式取得子树

Question

我的需求是，将Treeview中指定的（以一个Entity为目标）TreeviewItem选中

这是我的Treeview的模板

<DataTemplate x:Key="SubCategoryTree">
                <TextBlock  Text="{Binding Path=SubCatDesc}" Tag="{Binding DocumentsList}" GotFocus="SubCategoeyGotFocus" />
            </DataTemplate>
            <HierarchicalDataTemplate ItemsSource="{Binding SubCategoryList}"  ItemTemplate="{StaticResource SubCategoryTree}"
                x:Key="CategoryTree" >
                <TextBlock Text="{Binding Description}" Tag="{Binding DocCatID}"></TextBlock>
            </HierarchicalDataTemplate>

Treeview，基本上没什么特别的

<TreeView x:Name="TvCategory" BorderThickness="0" ScrollViewer.HorizontalScrollBarVisibility="Disabled" ScrollViewer.VerticalScrollBarVisibility="Disabled"  ItemsSource="{Binding}" ItemTemplate="{StaticResource CategoryTree}" />

CategoryTree的格式是三层的，Category -N: SubCategroy -N: DocumentIndexs，Treeview里面我只需要用到前两层

这是我寻找所需子树的代码

for (int i = 0; i < TvCategory.Items.Count; i++)
                {
                    for (int j = 0; j < ((DocCategory)TvCategory.Items[i]).SubCategoryList.Count; j++)
                    {
                        if (((DocSubCategory)(((DocCategory)TvCategory.Items[i]).SubCategoryList[j])).SubCatDesc == selection.ToString())
                        {

                            TreeViewItem treeMainItem = TvCategory.ItemContainerGenerator.ContainerFromItem(TvCategory.Items[i]) as TreeViewItem;
                            treeMainItem.IsExpanded = true;

                            
                            TreeViewItem treeItem = treeMainItem.ItemContainerGenerator.ContainerFromItem(treeMainItem.Items[j]) as TreeViewItem;
                            treeItem.IsSelected = true;
                            break;
                        }
                    }
                }

 

代码走到黑体的部分以后，已经找到了指定的Entity，但就是无法以TreeviewItem的形式打开，treeItem老是为null，请问这是怎么回事呢？

有没有什么好的解决方式呢

我的需求是，将Treeview中指定的（以一个Entity为目标）TreeviewItem选中

Answer 1

您好 安道古人，

您可以尝试一下下面的代码：

  for (int i = 0; i < TvCategory.Items.Count; i++)
  {
    TreeViewItem catItem = TvCategory.ItemContainerGenerator.ContainerFromIndex(i) as TreeViewItem;
    if (catItem != null)
    {
      for (int j = 0; j < catItem.Items.Count; j++)
      {
        DocSubCategory subCatItem = catItem.Items[j] as DocSubCategory;
        if (subCatItem != null && subCatItem.SubCatDesc == selection.ToString())
        {

          TreeViewItem treeMainItem = catItem.ItemContainerGenerator.ContainerFromIndex(j) as TreeViewItem;
          treeMainItem.IsExpanded = true;

          TreeViewItem treeItem = treeMainItem.ItemContainerGenerator.ContainerFromItem(treeMainItem.Items[j]) as TreeViewItem;
          treeItem.IsSelected = true;
          break;
        }
      }
    }
  }

Aland Li

---

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Answer 2

您好 安道古人，

您可以尝试一下下面的代码：

 for (int i = 0; i < TvCategory.Items.Count; i++)

 {

  TreeViewItem catItem = TvCategory.ItemContainerGenerator.ContainerFromIndex(i) as TreeViewItem;

  if (catItem != null)

  {

   for (int j = 0; j < catItem.Items.Count; j++)

   {

    DocSubCategory subCatItem = catItem.Items[j] as DocSubCategory;

    if (subCatItem != null && subCatItem.SubCatDesc == selection.ToString())

    {



     TreeViewItem treeMainItem = catItem.ItemContainerGenerator.ContainerFromIndex(j) as TreeViewItem;

     treeMainItem.IsExpanded = true;



     TreeViewItem treeItem = treeMainItem.ItemContainerGenerator.ContainerFromItem(treeMainItem.Items[j]) as TreeViewItem;

     treeItem.IsSelected = true;

     break;

    }

   }

  }

 }

Aland Li

---

Please mark the replies as answers if they help and unmark if they don't. This can be beneficial to other community members reading the thread.

TreeViewItem treeMainItem = catItem.ItemContainerGenerator.ContainerFromIndex(j) as TreeViewItem;

这一部就取不到了

如果这样运行：

for (int i = 0; i < TvCategory.Items.Count; i++)
    {
     TreeViewItem catItem = TvCategory.ItemContainerGenerator.ContainerFromIndex(i) as TreeViewItem;
     if (catItem != null)
     {
      for (int j = 0; j < catItem.Items.Count; j++)
      {
       DocSubCategory subCatItem = catItem.Items[j] as DocSubCategory;
       if (subCatItem != null && subCatItem.SubCatDesc == selection.ToString())
       {

        //TreeViewItem treeMainItem = catItem.ItemContainerGenerator.ContainerFromIndex(j) as TreeViewItem;
        //treeMainItem.IsExpanded = true;
        catItem.IsExpanded = true;

        TreeViewItem treeItem = catItem.ItemContainerGenerator.ContainerFromItem(subCatItem) as TreeViewItem;
        treeItem.IsSelected = true;
        break;
       }
      }
     }
    }

用quickwatch 会发现 catItem.ItemContainerGenerator的Items为null

而catItem.ItemContainerGenerator的host和peer里面有我想要的TreeviewItem，但这两个是non-Public的

Answer 3

Hi 安道故人,

这样的话可能要遍历VisualTree了，您可以用XamlPad之类的工具查看一下VisualTree。

Aland Li

---

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