WPF 树视图获取父节点的对象
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WPF treeview get object of parent node
提问by Matthias
I have a treeview with the following structure:
我有一个具有以下结构的树视图：
Attribute1
--Value11
--Value12
Attribute2
--Value21
--...
...
The treeview is populated with an HierarchicalDataTemplateof custom classes Attributeand Value.
树视图填充了HierarchicalDataTemplate自定义类Attribute和Value.
Now I need to get the parent (attribute) of the currently selected item (value).
现在我需要获取当前选定项（值）的父项（属性）。
What I tried:
我试过的：
DependencyObject obj = treeViewAttributes.ItemContainerGenerator.ContainerFromItem(treeViewAttributes.Items.CurrentItem);
DependencyObject parentNode = ((TreeViewItem)obj).Parent;
Attribute parentAttribute = treeViewAttributes.ItemContainerGenerator.ItemFromContainer(obj) as AttributeType;
However the first line doesn't retrieve the selected object, but the root node. And ContainerFromItem(treeViewAttributes.SelectedItem)returns null.
然而，第一行不检索选定的对象，而是检索根节点。并ContainerFromItem(treeViewAttributes.SelectedItem)返回null。
回答by E Vakhovsky
WPF has a reason not to easily return a parent of a tree node. It basically forces you to think of a TreeView in terms of logical vs visual representation. Every node in a tree logically contains an object which on its own level is always created prior to its child, so the best approach to take when you know that you will need access to a parent node is to have a reference to a parent within a child when the child is being created since the parent already always exists. This approach is way more efficient than walking the visual tree in search of a parent
WPF 有理由不轻易返回树节点的父节点。它基本上迫使您根据逻辑与视觉表示来考虑 TreeView。树中的每个节点在逻辑上都包含一个对象，该对象在其自身级别上始终先于其子节点创建，因此当您知道需要访问父节点时采取的最佳方法是在一个对象中引用父节点child 当正在创建 child 时，因为 parent 已经始终存在。这种方法比在视觉树中寻找父节点更有效
回答by Johannes91
I tried running through treeView and use GetHashCode for finding parent treeViewItem and it worked well for me. I don't know how the performance is, but I think that should not be a problem:
我尝试通过 treeView 运行并使用 GetHashCode 来查找父 treeViewItem，它对我来说效果很好。我不知道性能如何，但我认为这应该不是问题：
private TreeViewItem GetParent(TreeViewItem root, TreeViewItem child)
{
//Step 1: Search at current level
foreach (TreeViewItem item in root.Items)
{
if (item.GetHashCode() == child.GetHashCode())
{
return root;
}
}
//Step 2: Still not found, so step deeper
TreeViewItem buffer;
foreach (TreeViewItem item in root.Items)
{
buffer = GetParent(item, child);
if (buffer != null)
{
return buffer;
}
}
//Not found anything
return null;
}
回答by Adam
Use the helper class in this blog
使用本博客中的助手类
https://rachel53461.wordpress.com/2011/10/09/navigating-wpfs-visual-tree/
https://rachel53461.wordpress.com/2011/10/09/navigating-wpfs-visual-tree/
/// <summary>
/// Returns the first ancester of specified type
/// </summary>
public static T FindAncestor<T>(DependencyObject current)
where T : DependencyObject
{
current = VisualTreeHelper.GetParent(current);
while (current != null)
{
if (current is T)
{
return (T)current;
}
current = VisualTreeHelper.GetParent(current);
};
return null;
}
Then you can get the parent with this call
然后你可以通过这个电话获得父母
var parent = VisualTreeHelpers.FindAncestor<Attribute>(Value);
回答by Microsoft DN
Try following code
试试下面的代码
private void yourTreeView_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
{
if (sender is TreeView && ((TreeViewItem)((TreeView)sender).SelectedItem).Parent != null)
{
TreeViewItem parent = (TreeViewItem)((TreeViewItem)((TreeView)sender).SelectedItem).Parent; // This will give you the parent
}
}
