The TreeView control supports declarative binding to an XML file by using XmlDataSource controls. You can bind a TreeView control to an XML file by creating an XmlDataSource control that represents the XML file and then assigning that XmlDataSource to your TreeView control. Furthermore, you can control how and what data is bound to the TreeView control by using several techniques, which include the following:

• If the data source is an XML file, alter the data by performing an XML transformation before the XML file is bound to the control. For more information, see XSLT Transformations.

• Create a custom DataBindings property that controls which fields in the XML file populate the TreeNode properties, such as the Text property, the Value property, the NavigateUrl property, and others. For more information, see Customizing the Look and Feel of the TreeView Web Server Control.

For more information about binding to an XML file, see Binding to Hierarchical Data. For a step-by-step example, see Walkthrough: Displaying Hierarchical Data in a TreeView Control.

The TreeView control supports declarative binding to a site-map file by using SiteMapDataSource controls. When binding to an instance of the SiteMapDataSource control, the Title and Url properties of each SiteMapNode are automatically associated with the Text and NavigateUrl properties of each TreeNode object in the TreeView control, so there is no need to create custom data bindings. For more information and an example of binding a TreeView control to a site map, see TreeView.

The populate-on-demand feature allows you to specify that a node not be populated with data when the TreeView control initially renders. Instead, the TreeNode control will request child-node data when a user clicks the node. When the PopulateOnDemand property of a TreeNode control is set to true, the TreeNodePopulate event occurs when a user clicks the node to expand it. You can create an event handler to retrieve data dynamically when the TreeNodePopulate event is raised, which allows tree data to be retrieved as needed. For more information, see Server Event Handling in ASP.NET Web Pages.

In addition to using a class that derives from DataSourceControl to declaratively bind data to the TreeView control, the TreeView control provides a DataSource property and a DataBind method for data binding.

Reference

Concepts