RequiredFieldValidator Control

Definition and Usage

The RequiredFieldValidator control is used to make an input control a required field.

With this control, the validation fails if the input value does not change from its initial value. By default, the initial value is null.

Note: Leading and trailing spaces of the input value are removed before validation.

Note: The InitialValue property does not set the default value for the input control. It indicates the value that you do not want the user to enter in the input control.

Properties

Example 1

The following example contains two forms in an .aspx file. The first form has a label with the text "Please enter a number from 1 through 100", an input box to input a number, a RangeValidator control that checks that the input value is a number from 1 through 100, a RequiredFieldValidator control that checks that the input field isn't empty, and a submit button. The second page is activated by the submit button on the first page, and displays a response. If the input value validates as an error, an error message is displayed:

<%@ Page 
Inherits="System.Web.UI.MobileControls.MobilePage"%>
<%@ Register TagPrefix="Mobile"
Namespace="System.Web.UI.MobileControls"
Assembly="System.Web.Mobile" %>

<script runat="server">
sub page2(Sender as Object,E as EventArgs)
if Page.IsValid then
  ActiveForm=f2
  lbl2.Text="You entered number " & txt1.text
end if
end sub
</script>

<Mobile:Form id="f1" runat="server">
  <Mobile:Label runat="server">
  Please enter a number from 1 through 100
  </Mobile:Label>

  <Mobile:TextBox id="txt1" runat="server"/>

  <Mobile:RangeValidator
  ControlToValidate="txt1"
  Type="Integer"
  MaximumValue="100"
  MinimumValue="1"
  Text="Invalid number"
  runat="server" />

  <Mobile:RequiredFieldValidator
  ControlToValidate="txt1" 
  Text="A number is required"
  runat="server" />

  <Mobile:Command runat="server"
  OnClick="page2">Submit
  </Mobile:Command>
</Mobile:Form>

<Mobile:Form id="f2" runat="server">
  <Mobile:Label id="lbl2" runat="server" />
</Mobile:Form>

Jump to: Top of Page or HOME or Printer friendly page

Search W3Schools:

What Others Say About Us

Does the world know about us? Check out these places:

Dogpile Alta Vista MSN Google Excite Lycos Yahoo Ask Jeeves

We Help You For Free. You Can Help Us!

• Tell your newsgroup or mailing list
• Link to us from your pages
• Help us correct errors and broken links
• Help us with spelling and grammar
• Validate the XHTML code of this page

W3Schools is for training only. We do not warrant its correctness or its fitness for use. The risk of using it remains entirely with the user. While using this site, you agree to have read and accepted our terms of use and privacy policy.

Copyright 1999-2002 by Refsnes Data. All Rights Reserved

How we converted to XHTML