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Headers

HeaderTemplate element of the RadComboBox, allows the header of the items in the drop-down list, to be customized. The header is especially useful if your item template displays attributes in multiple columns, although it can be used with any RadComboBox item style. It could be used even when RadComboBox does not have an ItemTemplate defined. Like the ItemTemplate, the HeaderTemplate can include any HTML element.

The following example shows how to create a multi-column RadComboBox with a header that labels the columns of each item.

note

Both, the HeaderTemplate and ItemTemplate , lay out items using a table that fixes column width, so that the header and items line up properly.

Defining HeaderTemplates inline

<telerik:radcombobox 
    id="RadComboBox1" 
    runat="server"
    height="190px" 
    width="420px"
    markfirstmatch="true" 
    datasourceid="MyDataSource" 
    highlighttemplateditems="true"
    onitemdatabound="RadComboBox1_ItemDataBound"> 
<HeaderTemplate>   
    <table style="width: 415px; text-align: left">     
        <tr>        
            <td style="width: 125px;">Company Name</td>        
            <td style="width: 125px;">City</td>        
            <td style="width: 125px;">Title</td>        
            <td style="width: 40px;" align="right">            
                <img alt="" src="img/help.gif" />        
            </td>     
        </tr>   
    </table> 
</HeaderTemplate> 
<ItemTemplate>   
    <table style="width: 415px; text-align: left">     
    <tr>        
        <td style="width: 125px;">            
            <%# DataBinder.Eval(Container.DataItem, "CompanyName") %>        
        </td>        
        <td style="width: 125px;">
            <%# DataBinder.Eval(Container.DataItem, "City") %>        
        </td>        
        <td style="width: 125px;">
            <%# DataBinder.Eval(Container.DataItem, "ContactTitle") %>        
        </td>        
        <td style="width: 40px;"></td>     
    </tr>  
    </table> 
</ItemTemplate>
</telerik:radcombobox>

ItemDataBound


protected void RadComboBox1_ItemDataBound(object sender, RadComboBoxItemEventArgs e)
{  
    e.Item.Text = ((DataRowView)e.Item.DataItem)["CompanyName"].ToString() + "; " +
                  ((DataRowView)  e.Item.DataItem)["City"].ToString() + "; " +                
                  ((DataRowView)e.Item.DataItem)["ContactTitle"].ToString();
}


Protected Sub RadComboBox1_ItemDataBound(ByVal sender As Object, ByVal e As RadComboBoxItemEventArgs)

    e.Item.Text = (DirectCast(e.Item.DataItem, DataRowView))("CompanyName").ToString() + "; " +
                  (DirectCast(e.Item.DataItem, DataRowView))("City").ToString() + "; " +
                  (DirectCast(e.Item.DataItem, DataRowView))("ContactTitle").ToString()
End Sub

The result looks as follows:

MultiColumn ComboBox

Defining HeaderTemplates at run-time

<telerik:radcombobox 
    id="RadComboBox1" 
    runat="server" 
    radcomboboximageposition="Right"
    autopostback="true">            
</telerik:radcombobox>


protected override void OnInit(EventArgs e)
{    
    RadComboBox1.HeaderTemplate = new HeaderTemplate();    
    base.OnInit(e);
}
protected void Page_Load(object sender, EventArgs e)
{    
    if (!Page.IsPostBack)    
    {        
        RadComboBox1.Items.Add(new RadComboBoxItem("RadComboBoxItem4"));        
        RadComboBox1.Items.Add(new RadComboBoxItem("RadComboBoxItem5"));    
    }

    RadComboBox1.DataBind();
}

class HeaderTemplate : ITemplate
{    
    public void InstantiateIn(Control container)    
    {        
        HtmlTable table = new HtmlTable();        
        HtmlTableRow row = new HtmlTableRow();
        HtmlTableCell cell = new HtmlTableCell();        
        cell.InnerText = "Value";        
        row.Controls.Add(cell);
        HtmlTableCell cell1 = new HtmlTableCell();        
        cell1.InnerText = "Text";        
        row.Controls.Add(cell1);
        table.Controls.Add(row);        
        container.Controls.Add(table);    
    }
}



Protected Overloads Overrides Sub OnInit(ByVal e As EventArgs)

    RadComboBox1.HeaderTemplate = New HeaderTemplate()
    MyBase.OnInit(e)

End Sub
Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)

    If Not Page.IsPostBack Then

        RadComboBox1.Items.Add(New RadComboBoxItem("RadComboBoxItem4"))
        RadComboBox1.Items.Add(New RadComboBoxItem("RadComboBoxItem5"))

    End If

    RadComboBox1.DataBind()

End Sub

Class HeaderTemplate Implements ITemplate 

    Public Sub InstantiateIn(ByVal container As Control) Implements ITemplate.InstantiateIn

        Dim table As New HtmlTable()
        Dim row As New HtmlTableRow()
        Dim cell As New HtmlTableCell()
        cell.InnerText = "Value"
        row.Controls.Add(cell)
        Dim cell1 As New HtmlTableCell()
        cell1.InnerText = "Text"
        row.Controls.Add(cell1)
        table.Controls.Add(row)
        container.Controls.Add(table)

    End Sub

End Class

Accessing controls in HeaderTemplate

You can find any control embedded in the RadComboBox' HeaderTemplate, like:


Button btn = (Button)RadComboBox1.Header.FindControl("Button1");
btn.Text = "New Text";


Dim btn As Button = CType(RadComboBox1.Header.FindControl("Button1"), Button)
btn.Text = "New Text"

See Also