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CustomValidator.ServerValidate Event

Occurs when validation is performed on the server.

Namespace:  System.Web.UI.WebControls
Assembly:  System.Web (in System.Web.dll)

'Declaration
Public Event ServerValidate As ServerValidateEventHandler
'Usage
Dim instance As CustomValidator 
Dim handler As ServerValidateEventHandler 

AddHandler instance.ServerValidate, handler
<asp:CustomValidator OnServerValidate="ServerValidateEventHandler" />

The ServerValidate event is raised when validation is performed on the server. This event is used to provide a custom validation routine for an input control, such as a TextBox control.

For more information about handling events, see Events and Delegates.

TopicLocation
Walkthrough: Validating User Input in a Web Forms PageBuilding ASP .NET Web Applications in Visual Studio

The following code example demonstrates how to specify and code a handler for a server-side CustomValidator control. It creates a custom validation routine, validates the value of a TextBox control for an even number, and then displays the result of the validation.

Security noteSecurity Note:

This example has a text box that accepts user input, which is a potential security threat. By default, ASP.NET Web pages validate that user input does not include script or HTML elements. For more information, see Script Exploits Overview.

<%@ Page Language="VB" AutoEventWireup="True" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title>CustomValidator ServerValidate Example</title>
<script runat="server">

      Sub ValidateBtn_OnClick(sender As Object, e As EventArgs) 

         ' Display whether the page passed validation. 
         If Page.IsValid Then 

            Message.Text = "Page is valid." 

         Else 

            Message.Text = "Page is not valid!" 

         End If 

      End Sub 

      Sub ServerValidation(source As Object, args As ServerValidateEventArgs)

         Try  

            ' Test whether the value entered into the text box is even. 
            Dim num As Integer = Integer.Parse(args.Value)
            args.IsValid = ((num mod 2) = 0)

         Catch ex As Exception

            args.IsValid = false

         End Try 

      End Sub

   </script>    

</head>
<body>

   <form id="form1" runat="server">

      <h3>CustomValidator ServerValidate Example</h3>

      <asp:Label id="Message"
           Text="Enter an even number:" 
           Font-Names="Verdana" 
           Font-Size="10pt" 
           runat="server"
           AssociatedControlID="Text1" />

      <br />

      <asp:TextBox id="Text1" 
           runat="server" />

      &nbsp;&nbsp;

      <asp:CustomValidator id="CustomValidator1"
           ControlToValidate="Text1"
           Display="Static"
           ErrorMessage="Not an even number!"
           ForeColor="green"
           Font-Names="verdana" 
           Font-Size="10pt"
           OnServerValidate="ServerValidation"
           runat="server"/>

      <br />

      <asp:Button id="Button1"
           Text="Validate" 
           OnClick="ValidateBtn_OnClick" 
           runat="server"/>

   </form>

</body>
</html>

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0
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