Using the CustomValidator control to perform server-side validations (VB) : CustomValidator « Validation « ASP.NET Tutorial

<%@ Page Language="VB" %>

<script runat="server">
   Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs)
       If Page.IsValid Then
          Label1.Text = "VALID ENTRY!"
       End If
   End Sub

   Sub ValidateNumber(sender As Object, args As ServerValidateEventArgs)
          Dim num As Integer = Integer.Parse(args.Value)
          args.IsValid = ((num mod 5) = 0)
       Catch ex As Exception
          args.IsValid = False
       End Try
   End Sub

<html xmlns="" >
<head id="Head1" runat="server">
    <form id="form1" runat="server">
            <asp:TextBox ID="TextBox1" 
            <asp:CustomValidator ID="CustomValidator1" 
             Runat="server" ControlToValidate="TextBox1" 
             ErrorMessage="Number must be divisible by 5" 
            <asp:Button ID="Button1" OnClick="Button1_Click" 
             Runat="server" Text="Button"></asp:Button>
            <asp:Label ID="Label1" Runat="server"></asp:Label>

8.3.1.You can associate a custom validation function with the CustomValidator control.
8.3.2.Validate a blank field
8.3.3.Performing validation against no particular field.
8.3.4.Use both client side and server side script to validate (
8.3.5.Create user control based on CustomValidator
8.3.6.Using the CustomValidator control to perform client-side validations
8.3.7.Using the CustomValidator control to perform server-side validations (C#)
8.3.8.Using the CustomValidator control to perform server-side validations (VB)
8.3.9.Custom validator with Javascript
8.3.10.CustomValidator for login page
8.3.11.CustomValidator for login page (VB)