Build Your Own ASP.NET 2.0 Web Site Using C# & VB, Second Edition

<asp:Panel id="myPanel" runat="server">

<p>Username: <asp:TextBox id="usernameTextBox" Columns="30"

runat="server" /></p>

<p>Password: <asp:TextBox id="passwordTextBox"

TextMode="Password" Columns="30" runat="server" />

</p>

</asp:Panel>

<asp:Button id="hideButton" Text="Hide Panel" OnClick="HidePanel"

runat="server" />

The code above places two TextBox controls within a Panel control. The Button

control is outside of the panel. The HidePanel subroutine would then control

the Panel’s visibility by setting its Visible property to False:

Visual Basic

Public Sub HidePanel(s As Object, e As EventArgs)

myPanel.Visible = False

End Sub

C#

public void HidePanel(Object s, EventArgs e)

{

myPanel.Visible = false;

}

In this case, when the user clicks the button, the Click event is raised and the

HidePanel subroutine is called, which sets the Visible property of the Panel

control to False.

List Controls

Here, we’ll meet the ASP.NET controls that display simple lists of elements:

ListBox, DropDownList, CheckBoxList, RadioButtonList, and BulletedList.

DropDownList

A DropDownList control is similar to the HTML select element. The

DropDownList control allows you to select one item from a list using a drop-down

menu.

<asp:DropDownList id="ddlFavColor" runat="server">

<asp:ListItem Text="Red" value="red" />

<asp:ListItem Text="Blue" value="blue" />

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Chapter 4: Constructing ASP.NET Web Pages

<asp:ListItem Text="Green" value="green" />

</asp:DropDownList>

The most useful event that this control provides is SelectedIndexChanged. This

event is exposed by other list controls, such as the CheckBoxList and

RadioButtonList controls, allowing for easy programmatic interaction with the

control. These controls can also be bound to a database, allowing you to extract

dynamic content into a drop-down menu.

ListBox

A ListBox control equates to the HTML select element with either the multiple

or size attribute set (size would need to be set to a value of 2 or more). If you

set the SelectionMode attribute to Multiple, the user will be able to select more

than one item from the list, as in this example:

<asp:ListBox id="listTechnologies" runat="server"

SelectionMode="Multiple">

<asp:ListItem Text="ASP.NET" Value="aspnet" />

<asp:ListItem Text="JSP" Value="jsp" />

<asp:ListItem Text="PHP" Value="php" />

<asp:ListItem Text="CGI" Value="cgi" />

<asp:ListItem Text="ColdFusion" Value="cf" />

</asp:ListBox>

RadioButtonList

Like the RadioButton control, the RadioButtonList control represents radio

buttons. However, the RadioButtonList control represents a list of radio buttons

and uses more compact syntax. Here’s an example:

<asp:RadioButtonList id="favoriteColor" runat="server">

<asp:ListItem Text="Red" Value="red" />

<asp:ListItem Text="Blue" Value="blue" />

<asp:ListItem Text="Green" Value="green" />

</asp:RadioButtonList>

CheckBoxList

As you may have guessed, the CheckBoxList control represents a group of check

boxes; it’s equivalent to using several CheckBox controls in row:

<asp:CheckBoxList id="favoriteFood" runat="server">

<asp:ListItem Text="Pizza" Value="pizza" />

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List Controls