# Binding to Hierarchical DataSource
Some data sources are inherently hierarchical. These include **SiteMapDataSource** and **XmlDataSource**. When data-bound to these types of data sources, **RadPanelBar** automatically creates the panel item hierarchy. There is no need to use the **DataFieldID** and **DataFieldParentID** properties.
## Binding to SiteMapDataSource
When binding to **SiteMapDataSource**, there is no need to set any properties to map fields from the data source to properties of the panel items. This is because site maps have a strictly defined structure.
The **SiteMapDataSource** control defines the structure of your Web site. You can have only one sitemap per site. By default the **SiteMapDataSource** control uses the default Site Navigation Provider. This provider lets you define the structure of your site, separating the real page structure of the site on one hand, and the UI presentation on the other.
The default site navigation provider is XML-based. It should stay in the root level of your project and should be named **web.sitemap**. Using the Site Navigation API provided in ASP.NET v2.0, you can write your own Site Navigation Provider and expose the navigation information from any back-end system, if needed.
## Setting the SiteMapDataSource control
Before adding the **SiteMapDataSource** control to your page, you need to add the Site Navigation Provider.
* In the Solution Explorer, choose **Add New Item**... In the templates dialog, select **Site Map**:
* Click the Add button. Visual Studio generates the web.sitemap file with the initial code:
```XML
```
* Populate the Web.sitemap file. Here is an example:
```XML
```
> caution The url must be unique for each node. Avoid using backslashes (`\`) for your URLs. Backslashes may cause problems with some browsers. Instead, we use the slash character (`/`).
* Drag a **SiteMapDataSource** instance from the Toolbox to your Web page.
* Set the **ShowStartingNode** property of the **SiteMapDataSource** component to **False**. This allows you to use multiple panel items at the root level.
## Binding the SiteMapDataSource to Telerik RadPanelBar
1. From the **RadPanelBar** property pane, set the **DataSourceID** to the **ID** of the **SiteMapDataSource** control.
2. Each **siteMapNode** has three attributes which are mapped automatically to the respective properties:
* **url** - Maps to the **NavigateUrl** property. The path can be either relative (using the \~/), or absolute.
* **title** - Maps to the **Text** property.
* **description** - Maps to the **ToolTip** property.
3. To set additional properties or overwrite already populated fields, use the **ItemDataBound** event. The example below overwrites the **TooTip** property with the Text value of the item and sets the **Value** property to a concatenated string of \[Text] + "\_Value".
```C#
protected void RadPanelBar1_ItemDataBound( object sender, Telerik.Web.UI.RadPanelBarEventArgs e)
{
e.Item.ToolTip = (string )DataBinder.Eval(e.Item.DataItem, "title");
e.Item.Value = (string)DataBinder.Eval(e.Item.DataItem, "title") + "_Value";
}
```
```VB.NET
Protected Sub RadPanelBar1_ItemDataBound(ByVal sender As Object, ByVal e As Telerik.Web.UI.RadPanelBarEventArgs)
e.Item.ToolTip = CStr(DataBinder.Eval(e.Item.DataItem, "title"))
e.Item.Value = CStr(DataBinder.Eval(e.Item.DataItem, "title")) + "_Value"
End Sub
```
## Binding to XmlDataSource
When binding to an **XmlDataSource**, **RadPanelBar** creates the panel item hierarchy automatically. However, unlike **SiteMapDataSource**, properties such as **Text** and **NavigateUrl** are **not** automatically populated.
Consider the following example:
* Add the following xml file in the App_Data folder:
```XML
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