Creating Link Buttons

Link buttons let you handle hyperlinks with Visual Basic code. As with hyperlink controls, you set the text in a link button with the Text property, and as with hyperlink controls, link buttons are supported with HTML <a> elements. However, you can add code to the Click and Command event handlers for link buttons, which you can't do for hyperlink controls.

You can see a link button at work in the LinkButtons example on the CD-ROM in Figure 17.7. In this case, when the user clicks the hyperlink, I make a label with the text "Sorry, no more information is available" and a solid border visible, as you can see in that figure. To make that label visible, all I need to do is to add this code to the link button's Click event:

   Private Sub LinkButton1_Click(ByVal sender As System.Object, _
       ByVal e As System.EventArgs) Handles LinkButton1.Click
       Label1.Visible = True
   End Sub

And that's all it takes. Here's WebForm1.aspx for the LinkButtons example:

<%@ Page Language="vb" AutoEventWireup="false"
Codebehind="WebForm1.aspx.vb" Inherits="LinkButtons.WebForm1"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
  <HEAD>
    <title>LinkButtons example</title>
    <meta name="GENERATOR" content="Microsoft Visual Studio.NET 7.0">
    <meta name="CODE_LANGUAGE" content="Visual Basic 7.0">
    <meta name=vs_defaultClientScript content="JavaScript">
    <meta name=vs_targetSchema content=
    "http://schemas.microsoft.com/intellisense/ie5">
  </HEAD>
  <body MS_POSITIONING="GridLayout">

    <form id="Form1" method="post" runat="server">
<asp:LinkButton id=LinkButton1 style="Z-INDEX: 101; LEFT: 162px;
POSITION: absolute; TOP: 75px" runat="server">here</asp:LinkButton>
<asp:Label id=Label3 style="Z-INDEX: 104; LEFT: 191px; POSITION:
absolute; TOP: 75px" runat="server">for more information.</asp:Label>
<asp:Label id=Label2 style="Z-INDEX: 103; LEFT: 128px; POSITION:
absolute; TOP: 75px" runat="server">Click</asp:Label>
<asp:Label id=Label1 style="Z-INDEX: 102; LEFT: 101px; POSITION:
absolute; TOP: 130px" runat="server" Width="243px" Height="26px"
BorderStyle="Solid" BorderWidth="1px" Visible="False">Sorry, no more
information is available.</asp:Label>

    </form>

  </body>
</HTML>

And here's WebForm1.aspx.vb for the LinkButtons example:

Public Class WebForm1
    Inherits System.Web.UI.Page
    Protected WithEvents Label1 As System.Web.UI.WebControls.Label
    Protected WithEvents Label2 As System.Web.UI.WebControls.Label
    Protected WithEvents Label3 As System.Web.UI.WebControls.Label
    Protected WithEvents LinkButton1 As _
        System.Web.UI.WebControls.LinkButton

#Region " Web Form Designer Generated Code "

    'This call is required by the Web Form Designer.
    <System.Diagnostics.DebuggerStepThrough()> _
        Private Sub InitializeComponent()
    End Sub

    Private Sub Page_Init(ByVal sender As System.Object, ByVal _
        e As System.EventArgs) Handles MyBase.Init
        'CODEGEN: This method call is required by the Web Form Designer
        'Do not modify it using the code editor.
        InitializeComponent()
    End Sub

#End Region

    Private Sub Page_Load(ByVal sender As System.Object, ByVal _
        e As System.EventArgs) Handles MyBase.Load
        'Put user code to initialize the page here
    End Sub

    Private Sub LinkButton1_Click(ByVal sender As System.Object, _
        ByVal e As System.EventArgs) Handles LinkButton1.Click
        Label1.Visible = True
    End Sub
End Class