Data Binding in Templates
When item templates are used, the controls in the template, need to display information associated with RadComboBox item data. Otherwise, the items will all appear the same. For example, consider a simple RadComboBox with a button in the item template:
<telerik:radcombobox id="RadComboBox1" runat="server" skin="Default">
<ItemTemplate>
<asp:Button ID="Button1" runat="server" Text="Button" />
</ItemTemplate>
<Items>
<telerik:RadComboBoxItem runat="server" Text="One" />
<telerik:RadComboBoxItem runat="server" Text="Two" />
<telerik:RadComboBoxItem runat="server" Text="Three" />
</Items>
</telerik:radcombobox>
When you run the application, RadComboBox displays a list of identical buttons in its drop-down list:
This is hardly useful! To override the Text property of the button in the template, the DataBinder.Eval statement is used, just as in the example below:
<telerik:radcombobox id="RadComboBox1" runat="server" skin="Default">
<ItemTemplate>
<asp:Button ID="Button1" runat="server" Text='<%# DataBinder.Eval(Container, "Text") %>' />
</ItemTemplate>
<Items>
<telerik:RadComboBoxItem runat="server" Text="One" />
<telerik:RadComboBoxItem runat="server" Text="Two" />
<telerik:RadComboBoxItem runat="server" Text="Three" />
</Items>
</telerik:radcombobox>
In the DataBinder.Eval statement, Container is the RadComboBoxItem and "Text" identifies the Text property of that item. (If you wanted to bind to the Value property, you could use the string "Value" instead.)
In this example, the first parameter to the DataBinder.Eval statement is Container , because the items are statically bound. If the RadComboBox is bound to a data source, the Container.DataItem statement should be used instead. That is <%#DataBinder.Eval(Container.DataItem, "Text") %>
In addition to adding a DataBinder.Eval statement, you must also explicitly call the DataBind method for the items so that the template has access to the Text property:
protected void Page_Load(object sender, EventArgs e)
{
for (int i = 0; i < RadComboBox1.Items.Count; i++)
{
RadComboBox1.Items[i].DataBind();
}
}
Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
Dim i As Integer = 0
While i < RadComboBox1.Items.Count
RadComboBox1.Items(i).DataBind()
i = i + 1
End While
End Sub
Now the text of the RadComboBox items appears on the buttons:
