Makes the associated input control a required field.
<AspNetHostingPermissionAttribute(SecurityAction.InheritanceDemand, Level := AspNetHostingPermissionLevel.Minimal)> _ <AspNetHostingPermissionAttribute(SecurityAction.LinkDemand, Level := AspNetHostingPermissionLevel.Minimal)> _ Public Class RequiredFieldValidator _ Inherits BaseValidator
Dim instance As RequiredFieldValidator
[AspNetHostingPermissionAttribute(SecurityAction.InheritanceDemand, Level = AspNetHostingPermissionLevel.Minimal)] [AspNetHostingPermissionAttribute(SecurityAction.LinkDemand, Level = AspNetHostingPermissionLevel.Minimal)] public class RequiredFieldValidator : BaseValidator
[AspNetHostingPermissionAttribute(SecurityAction::InheritanceDemand, Level = AspNetHostingPermissionLevel::Minimal)] [AspNetHostingPermissionAttribute(SecurityAction::LinkDemand, Level = AspNetHostingPermissionLevel::Minimal)] public ref class RequiredFieldValidator : public BaseValidator
public class RequiredFieldValidator extends BaseValidator
<asp:RequiredFieldValidator />
Use this control to make an input control a required field. The input control fails validation if its value does not change from the InitialValue property upon losing focus.
Multiple validators can be associated with the same input control. For example, a RequiredFieldValidator can be used to ensure input to a control, while at the same time a RangeValidator can be used to ensure that the input is within a specified data range.
When you use the RequiredFieldValidator control inside an UpdatePanel control, make sure that the validator control and the control it is associated with are in the same panel. For more information about using the UpdatePanel control for partial-page updates, see Partial-Page Rendering Overview.
For additional information on validation controls, see BaseValidator.
The markup rendered by default for this control might not conform to accessibility standards such as the Web Content Accessibility Guidelines 1.0 (WCAG) priority 1 guidelines. For details about accessibility support for this control, see ASP.NET Controls and Accessibility.
The following example demonstrates how to use the RequiredFieldValidator control to make sure that the user enters a value into the text box.
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 > <head> <title>RequiredField Validator Example</title> <script runat="server"> Sub ValidateBtn_Click(sender As Object, e As EventArgs) If Page.IsValid Then lblOutput.Text = "Required field is filled!" Else lblOutput.Text = "Required field is empty!" End If End Sub </script> </head> <body> <form id="form1" runat="server"> <h3>RequiredField Validator Example</h3> <table style="background-color:#eeeeee; padding:10"> <tr valign="top"> <td colspan="3"> <asp:Label ID="lblOutput" Text="Fill in the required field below" runat="server" AssociatedControlID="TextBox1"/> <br /> </td> </tr> <tr> <td colspan="3"> <b>Credit Card Information</b> </td> </tr> <tr> <td align="right"> Card Number: </td> <td> <asp:TextBox id="TextBox1" runat="server"/> </td> <td> <asp:RequiredFieldValidator id="RequiredFieldValidator2" ControlToValidate="TextBox1" Display="Static" ErrorMessage="*" runat="server"/> </td> </tr> <tr> <td></td> <td> <asp:Button id="Button1" Text="Validate" OnClick="ValidateBtn_Click" runat="server"/> </td> <td></td> </tr> </table> </form> </body> </html>
<%@ Page Language="C#" AutoEventWireup="True" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html > <head> <title>RequiredField Validator Example</title> <script runat="server"> void ValidateBtn_Click(Object sender, EventArgs e) { if (Page.IsValid) { lblOutput.Text = "Required field is filled!"; } else { lblOutput.Text = "Required field is empty!"; } } </script> </head> <body> <form id="form1" runat="server"> <h3>RequiredField Validator Example</h3> <table style="background-color:#eeeeee; padding:10"> <tr valign="top"> <td colspan="3"> <asp:Label ID="lblOutput" Text="Fill in the required field below" runat="server" AssociatedControlID="TextBox1"/> <br /> </td> </tr> <tr> <td colspan="3"> <b>Credit Card Information</b> </td> </tr> <tr> <td align="right"> Card Number: </td> <td> <asp:TextBox id="TextBox1" runat="server"/> </td> <td> <asp:RequiredFieldValidator id="RequiredFieldValidator2" ControlToValidate="TextBox1" Display="Static" ErrorMessage="*" runat="server"/> </td> </tr> <tr> <td></td> <td> <asp:Button id="Button1" Text="Validate" OnClick="ValidateBtn_Click" runat="server"/> </td> <td></td> </tr> </table> </form> </body> </html>
<html> <head> <script language="C#" runat=server> </script> </head> <body> <h3><font face="Verdana">RequiredField Validator Sample</font></h3> <p> <form runat="server"> <table bgcolor="#eeeeee" cellpadding=10> <tr valign="top"> <td colspan=3> <asp:Label ID="lblOutput" Text="Fill in the required field below" ForeColor="red" Font-Name="Verdana" Font-Size="10" runat=server /><br> </td> </tr> <tr> <td colspan=3> <font face=Verdana size=2><b>Credit Card Information</b></font> </td> </tr> <tr> <td align=right> <font face=Verdana size=2>Card Number:</font> </td> <td> <asp:TextBox id=TextBox1 runat=server /> </td> <td> <asp:RequiredFieldValidator id="RequiredFieldValidator2" ControlToValidate="TextBox1" Display="Static" Width="100%" runat=server> * </asp:RequiredFieldValidator> </td> </tr> <tr> <td></td> <td> <asp:Button id=Button1 text="Validate" OnClick="ValidateBtn_Click" runat=server /> </td> <td></td> </tr> </table> </form> </body> </html>
for operating in a hosted environment. Demand value: LinkDemand; Permission value: Minimal.
for operating in a hosted environment. Demand value: InheritanceDemand; Permission value: Minimal.
Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98