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HtmlInputHidden Class

.NET Framework 2.0

Allows programmatic access to the HTML <input type=hidden> element on the server.

Namespace: System.Web.UI.HtmlControls
Assembly: System.Web (in system.web.dll)

C#
C++
VB
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public class HtmlInputHidden : HtmlInputControl, IPostBackDataHandler
J#
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public class HtmlInputHidden extends HtmlInputControl implements IPostBackDataHandler
JScript
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public class HtmlInputHidden extends HtmlInputControl implements IPostBackDataHandler

You can use the HtmlInputHidden control to embed information that is hidden from the user within a <form> element. This information is sent when the Web page is posted back to the server. The HtmlInputHidden control provides a ServerChange event that is raised when the Value property changes values between posts to the server. This allows you to create an event handler that performs a custom set of instructions each time the event is raised.

NoteNote

The HtmlInputHidden control does not provide a built-in way to post back to the server. You must provide another control on the Web page that supports posting to the server, such as an HtmlButton control, to send the value of the control back to the server.

NoteNote

The ASP.NET page framework uses this HTML feature to automatically load and persist the view state of server controls on a page.

For a list of initial property values for an instance of HtmlInputHidden, see the HtmlInputHidden constructor.

The following code example demonstrates how to use an HtmlInputHidden control to store information on the Web page between posts to the server.

C#
JScript
VB
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<%@ Page Language="C#" AutoEventWireup="True" %>

<html>
<head>

   <script language="C#" runat="server">

      void Page_Load(object sender, EventArgs e) 
      {

         if (Page.IsPostBack) 
         {
            Span1.InnerHtml="Hidden value: <b>" + HiddenValue.Value + "</b>";
         }
      }

      void SubmitBtn_Click(object sender, EventArgs e) 
      {
         HiddenValue.Value=StringContents.Value;
      }

   </script>

</head>

<body>

   <form runat=server>

      <h3>HtmlInputHidden Sample</h3>

      <input id="HiddenValue" 
             type=hidden 
             value="Initial Value" 
             runat=server>

      Enter a string: 
 
      <input id="StringContents" 
             type=text 
             size=40 
             runat=server>

      <p>

      <input type=submit 
             value="Enter" 
             OnServerClick="SubmitBtn_Click" 
             runat=server>

      <p>

      <span id=Span1 runat=server>
         This label will display the previously entered string.
      </span>

   </form>

</body>
</html>
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0, 1.1, 1.0
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