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)
       Try
          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
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
    <title>CustomValidator</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        
            Number: 
            <asp:TextBox ID="TextBox1" 
             Runat="server"></asp:TextBox>
            <asp:CustomValidator ID="CustomValidator1" 
             Runat="server" ControlToValidate="TextBox1" 
             ErrorMessage="Number must be divisible by 5" 
             OnServerValidate="ValidateNumber"></asp:CustomValidator>
        
        
            <asp:Button ID="Button1" OnClick="Button1_Click" 
             Runat="server" Text="Button"></asp:Button>
        
        
            <asp:Label ID="Label1" Runat="server"></asp:Label>
        
    </div>
    </form>
</body>
</html>

8.3.CustomValidator
	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 (VB.net)
	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)