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HtmlInputHidden Class

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)
[AspNetHostingPermissionAttribute(SecurityAction.InheritanceDemand, Level = AspNetHostingPermissionLevel.Minimal)]
[AspNetHostingPermissionAttribute(SecurityAction.LinkDemand, Level = AspNetHostingPermissionLevel.Minimal)]
public class HtmlInputHidden : HtmlInputControl, 
	IPostBackDataHandler
<asp:HtmlInputHidden />

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.

<%@ 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 xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title>HtmlInputHidden Sample</title>
<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 id="form1" 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" />

      <br />

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

      <br />

      <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 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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