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title, ms.date, helpviewer_keywords, ms.assetid
| title | ms.date | helpviewer_keywords | ms.assetid | |
|---|---|---|---|---|
| How to: Bind a TreeView to Data That Has an Indeterminable Depth | 03/30/2017 |
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daddcd74-1b0f-4ffd-baeb-ec934c5e0f53 |
How to: Bind a TreeView to Data That Has an Indeterminable Depth
There might be times when you want to bind a xref:System.Windows.Controls.TreeView to a data source whose depth is not known. This can occur when the data is recursive in nature, such as a file system, where folders can contain folders, or a company's organizational structure, where employees have other employees as direct reports.
The data source must have a hierarchical object model. For example, an Employee class might contain a collection of Employee objects that are the direct reports of an employee. If the data is represented in a way that is not hierarchical, you must build a hierarchical representation of the data.
When you set the xref:System.Windows.Controls.ItemsControl.ItemTemplate%2A?displayProperty=nameWithType property and if the xref:System.Windows.Controls.ItemsControl generates an xref:System.Windows.Controls.ItemsControl for each child item, then the child xref:System.Windows.Controls.ItemsControl uses the same xref:System.Windows.Controls.ItemsControl.ItemTemplate%2A as the parent. For example, if you set the xref:System.Windows.Controls.ItemsControl.ItemTemplate%2A property on a data-bound xref:System.Windows.Controls.TreeView, each xref:System.Windows.Controls.TreeViewItem that is generated uses the xref:System.Windows.DataTemplate that was assigned to the xref:System.Windows.Controls.ItemsControl.ItemTemplate%2A property of the xref:System.Windows.Controls.TreeView.
The xref:System.Windows.HierarchicalDataTemplate enables you to specify the xref:System.Windows.Controls.ItemsControl.ItemsSource%2A for a xref:System.Windows.Controls.TreeViewItem, or any xref:System.Windows.Controls.HeaderedItemsControl, on the data template. When you set the xref:System.Windows.HierarchicalDataTemplate.ItemsSource%2A?displayProperty=nameWithType property, that value is used when the xref:System.Windows.HierarchicalDataTemplate is applied. By using a xref:System.Windows.HierarchicalDataTemplate, you can recursively set the xref:System.Windows.Controls.ItemsControl.ItemsSource%2A for each xref:System.Windows.Controls.TreeViewItem in the xref:System.Windows.Controls.TreeView.
Example
The following example demonstrates how to bind a xref:System.Windows.Controls.TreeView to hierarchical data and use a xref:System.Windows.HierarchicalDataTemplate to specify the xref:System.Windows.Controls.ItemsControl.ItemsSource%2A for each xref:System.Windows.Controls.TreeViewItem. The xref:System.Windows.Controls.TreeView binds to XML data that represents the employees in a company. Each Employee element can contain other Employee elements to indicate who reports to whom. Because the data is recursive, the xref:System.Windows.HierarchicalDataTemplate can be applied to each level.
[!code-xamlTreeViewWithUnknownDepth#1]