Working with the CheckBoxList Control

Working with the `CheckBoxList` Control

The CheckBoxList control renders a list of check boxes. The check boxes can be rendered horizontally or vertically. Unlike the other List controls, a user always can select multiple items when using a CheckBoxList control.

For example, the page in Listing 10.13 contains a CheckBoxList control that renders its list items in two columns (see Figure 10.12).

Figure 10.12. Displaying list items with the `CheckBoxList` control.

Listing 10.13. `ShowCheckBoxList.aspx`

<%@ Page Language="VB" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"> <script runat="server">     Protected  Sub btnSubmit_Click(ByVal sender As Object, ByVal e As EventArgs)         For Each item As ListItem In cblMovies.Items             if (item.Selected)                 lblMovie.Text &= "<li>" & item.Text             End If         Next     End Sub </script> <html xmlns="http://www.w3.org/1999/xhtml" > <head  runat="server">     <title>Show CheckBoxList</title> </head> <body>     <form  runat="server">     <div>     <asp:CheckBoxList                  DataSource         DataTextField="Title"         DataValueField="Id"         RepeatColumns="2"         Runat="server" />     <p>     <asp:Button                  Text="Submit"         OnClick="btnSubmit_Click"         Runat="server" />     </p>     <hr />     <asp:Label                  EnableViewState="false"         Runat="server" />     <asp:SqlDataSource                  SelectCommand="SELECT Id, Title FROM Movies"         ConnectionString="<%$ ConnectionStrings:Movies %>"         Runat="server" />     </div>     </form> </body> </html>

When you click the Submit button, the values of the Text property of any selected check boxes are displayed in a Label control. The selected check boxes are retrieved from the CheckBoxList control's Items property.

The CheckBoxList control includes three properties that affect its layout:

RepeatColumns The number of columns of check boxes to display.
RepeatDirection The direction in which the check boxes are rendered. Possible values are Horizontal and Vertical.
RepeatLayout Determines whether the check boxes are displayed in an HTML table. Possible values are Table and Flow.

Normally, a CheckBoxList control renders its list items in an HTML table. When the RepeatLayout property is set to the value Flow, the items are not rendered in a table.

Working with the CheckBoxList Control