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TextBox.ReadOnly Property

Gets or sets a value indicating whether the contents of the TextBox control can be changed.

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

[ThemeableAttribute(false)]
[BindableAttribute(true)]
public virtual bool ReadOnly { get; set; }
<asp:TextBox ReadOnly="True|False" />

Property Value

Type: System.Boolean
true if the contents of the TextBox control cannot be changed; otherwise, false. The default value is false.

Use the ReadOnly property to specify whether the contents of the TextBox control can be changed. Setting this property to true will prevent users from entering a value or changing the existing value. Note that the user of the TextBox control cannot change this property; only the developer can.

Important noteImportant

The Text value of a TextBox control with the ReadOnly property set to true is sent to the server when a postback occurs, but the server does no processing for a read-only text box. This prevents a malicious user from changing a Text value that is read-only. The value of the Text property is preserved in the view state between postbacks unless modified by server-side code.

This property cannot be set by themes or style sheet themes. For more information, see ThemeableAttribute and ASP.NET Themes and Skins.

The following code example demonstrates how to use the ReadOnly property to prevent any changes to the text displayed in the TextBox control.

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="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> MultiLine TextBox Example </title>
<script runat="server">

      protected void SubmitButton_Click(Object sender, EventArgs e)
      {

         Message.Text = "Thank you for your comment: <br />" + Comment.Text;

      }

      protected void Check_Change(Object sender, EventArgs e)
      {

         Comment.Wrap = WrapCheckBox.Checked;
         Comment.ReadOnly = ReadOnlyCheckBox.Checked;

      }

   </script>

</head>

<body>

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

      <h3> MultiLine TextBox Example </h3>


      Please enter a comment and click the submit button. 

      <br /><br /> 

      <asp:TextBox ID="Comment"
           TextMode="MultiLine"
           Columns="50"
           Rows="5"
           runat="server"/>

      <br />

      <asp:RequiredFieldValidator
           ID="Value1RequiredValidator"
           ControlToValidate="Comment"
           ErrorMessage="Please enter a comment.<br />"
           Display="Dynamic"
           runat="server"/>                         

      <asp:CheckBox ID="WrapCheckBox"
           Text="Wrap Text"
           Checked="True"
           AutoPostBack="True"
           OnCheckedChanged="Check_Change"
           runat="server"/>

      &nbsp;&nbsp;

      <asp:CheckBox ID="ReadOnlyCheckBox"
           Text="ReadOnly"
           Checked="False"
           AutoPostBack="True"
           OnCheckedChanged="Check_Change"
           runat="server"/>

      &nbsp;&nbsp;

      <asp:Button ID="SubmitButton"
           Text="Submit"
           OnClick="SubmitButton_Click"
           runat="server"/>

      <hr />

      <asp:Label ID="Message"
           runat="server"/>

   </form>

</body>
</html>

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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