DataList.HeaderTemplate Property
Gets or sets the template for the heading section of the DataList control.
Assembly: System.Web (in System.Web.dll)
<BrowsableAttribute(False)> <PersistenceModeAttribute(PersistenceMode.InnerProperty)> <TemplateContainerAttribute(GetType(DataListItem))> Public Overridable Property HeaderTemplate As ITemplate
Property Value
Type: System.Web.UI.ITemplateA System.Web.UI.ITemplate that contains the template for the heading section of the DataList control. The default value is null.
Use the HeaderTemplate property to control the contents of the heading section. The appearance of the header section is controlled by the HeaderStyle property.
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The ShowHeader property must be set to true for this property to be visible. |
To specify a template for the heading section, place the <HeaderTemplate> tags between the opening and closing tags of the DataList control. You can then list the contents of the template between the opening and closing <HeaderTemplate> tags.
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This control can be used to display user input, which might include malicious client script. Check any information that is sent from a client for executable script, SQL statements, or other code before displaying it in your application. You can use validation controls to verify user input before displaying the input text in a control. ASP.NET provides an input request validation feature to block script and HTML in user input. For more information, see Securing Standard Controls, How to: Protect Against Script Exploits in a Web Application by Applying HTML Encoding to Strings, and Validating User Input in ASP.NET Web Pages. |
The following code example demonstrates how to use the HeaderTemplate property to control the contents of the heading section of the DataList control.
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The following code sample uses the single-file code model and may not work correctly if copied directly into a code-behind file. This code sample must be copied into an empty text file that has an .aspx extension. For more information on the Web Forms code model, see ASP.NET Web Forms Page Code Model. |
<%@ Page Language="VB" AutoEventWireup="True" %> <%@ Import Namespace="System.Data" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <script runat="server"> Function CreateDataSource() As ICollection ' Create sample data for the DataList control. Dim dt As DataTable = New DataTable() dim dr As DataRow ' Define the columns of the table. dt.Columns.Add(New DataColumn("IntegerValue", GetType(Int32))) dt.Columns.Add(New DataColumn("StringValue", GetType(String))) dt.Columns.Add(New DataColumn("CurrencyValue", GetType(Double))) dt.Columns.Add(New DataColumn("ImageValue", GetType(String))) ' Populate the table with sample values. Dim i As Integer For i = 0 To 8 dr = dt.NewRow() dr(0) = i dr(1) = "Description for item " & i.ToString() dr(2) = 1.23 * (i + 1) dr(3) = "Image" & i.ToString() & ".jpg" dt.Rows.Add(dr) Next i Dim dv As DataView = New DataView(dt) Return dv End Function Sub Page_Load(sender As Object, e As EventArgs) ' Load sample data only once, when the page is first loaded. If Not IsPostBack Then ItemsList.DataSource = CreateDataSource() ItemsList.DataBind() End If End Sub Sub Button_Click(sender As Object, e As EventArgs) ' Set the repeat direction based on the selected value of the ' DirectionList DropDownList control. ItemsList.RepeatDirection = _ CType(DirectionList.SelectedIndex, RepeatDirection) ' Set the repeat layout based on the selected value of the ' LayoutList DropDownList control. ItemsList.RepeatLayout = CType(LayoutList.SelectedIndex, RepeatLayout) ' Set the number of columns to display based on the selected ' value of the ColumnsList DropDownList control. ItemsList.RepeatColumns = ColumnsList.SelectedIndex ' Show or hide the gridlines based on the value of the ' ShowBorderCheckBox. Note that gridlines are displayed ' only if the RepeatLayout property is set to Table. If ShowBorderCheckBox.Checked _ And ItemsList.RepeatLayout = RepeatLayout.Table Then ItemsList.BorderWidth = Unit.Pixel(1) ItemsList.GridLines = GridLines.Both Else ItemsList.BorderWidth = Unit.Pixel(0) ItemsList.GridLines = GridLines.None End If End Sub </script> <head runat="server"> <title>DataList Example</title> </head> <body> <form id="form1" runat="server"> <h3>DataList Example</h3> <asp:DataList id="ItemsList" BorderColor="black" CellPadding="5" CellSpacing="5" RepeatDirection="Vertical" RepeatLayout="Table" RepeatColumns="0" BorderWidth="0" runat="server"> <HeaderStyle BackColor="#aaaadd"> </HeaderStyle> <AlternatingItemStyle BackColor="Gainsboro"> </AlternatingItemStyle> <HeaderTemplate> List of items </HeaderTemplate> <ItemTemplate> Description: <br /> <%# DataBinder.Eval(Container.DataItem, "StringValue") %> <br /> Price: <%# DataBinder.Eval(Container.DataItem, "CurrencyValue", "{0:c}") %> <br /> <asp:Image id="ProductImage" AlternatingText='<%# DataBinder.Eval(Container.DataItem, "StringValue") %>' ImageUrl='<%# DataBinder.Eval(Container.DataItem, "ImageValue") %>' runat="server"/> </ItemTemplate> </asp:DataList> <hr /> <table cellpadding="5"> <tr> <th> Repeat direction: </th> <th> Repeat layout: </th> <th> Repeat columns: </th> <th> <asp:CheckBox id="ShowBorderCheckBox" Text="Show border" Checked="False" runat="server" /> </th> </tr> <tr> <td> <asp:DropDownList id="DirectionList" runat="server"> <asp:ListItem>Horizontal</asp:ListItem> <asp:ListItem Selected="True">Vertical</asp:ListItem> </asp:DropDownList> </td> <td> <asp:DropDownList id="LayoutList" runat="server"> <asp:ListItem Selected="True">Table</asp:ListItem> <asp:ListItem>Flow</asp:ListItem> </asp:DropDownList> </td> <td> <asp:DropDownList id="ColumnsList" runat="server"> <asp:ListItem Selected="True">0</asp:ListItem> <asp:ListItem>1</asp:ListItem> <asp:ListItem>2</asp:ListItem> <asp:ListItem>3</asp:ListItem> <asp:ListItem>4</asp:ListItem> <asp:ListItem>5</asp:ListItem> </asp:DropDownList> </td> <td> </td> </tr> </table> <asp:LinkButton id="RefreshButton" Text="Refresh DataList" OnClick="Button_Click" runat="server"/> </form> </body> </html>
Available since 1.1
HeaderStyle
System.Web.UI.ITemplate
DataList Class
System.Web.UI.WebControls Namespace
DataList Web Server Control Overview
Securing Standard Controls
How to: Protect Against Script Exploits in a Web Application by Applying HTML Encoding to Strings
Validating User Input in ASP.NET Web Pages
ASP.NET Web Forms Page Code Model

