Edit

Share via

TextBox.AddParsedSubObject(Object) Method

  • Reference

Definition

Namespace:
System.Web.UI.WebControls
Assembly:
System.Web.dll

Overridden to allow only literal controls to be added as the Text property.

protected:
 override void AddParsedSubObject(System::Object ^ obj);
protected override void AddParsedSubObject (object obj);
override this.AddParsedSubObject : obj -> unit
Protected Overrides Sub AddParsedSubObject (obj As Object)

Parameters

obj
Object

An Object that represents the parsed element.

Exceptions

HttpException

obj is not of type LiteralControl.

Examples

The following code example demonstrates how to override the AddParsedSubObject method in a custom server control so that it always sets the Text property to the parsed object's Text property if the parsed object is a Literal control, and throws an exception otherwise.

Important

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.

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS.Controls" Assembly="Samples.AspNet.CS" %>
<%@ 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>Custom TextBox - AddParsedSubObject - C# Example</title>
    </head>
    <body>
        <form id="Form1" method="post" runat="server">
            <h3>Custom TextBox - AddParsedSubObject - C# Example</h3>
            
            <aspSample:CustomTextBoxAddParsedSubObject 
              id="TextBox1" 
              runat="server">Hello World!
            </aspSample:CustomTextBoxAddParsedSubObject>
            
        </form>
    </body>
</html>

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB.Controls" Assembly="Samples.AspNet.VB" %>
<%@ 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 xmlns="http://www.w3.org/1999/xhtml" >
    <head>
        <title>Custom TextBox - AddParsedSubObject - VB.NET Example</title>
    </head>
    <body>
        <form id="Form1" method="post" runat="server">
            <h3>Custom TextBox - AddParsedSubObject - VB.NET Example</h3>
            
            <aspSample:CustomTextBoxAddParsedSubObject id="TextBox1" 
             runat="server">Hello World!</aspSample:CustomTextBoxAddParsedSubObject>
        </form>
    </body>
</html>

using System.Web;
using System.Security.Permissions;

namespace Samples.AspNet.CS.Controls
{
  [AspNetHostingPermission(SecurityAction.Demand, Level=AspNetHostingPermissionLevel.Minimal)]
  public sealed class CustomTextBoxAddParsedSubObject : System.Web.UI.WebControls.TextBox
  {
    protected override void AddParsedSubObject(object obj)
    {
      // If the object is a LiteralControl, then set this control's Text property.
      if (obj is System.Web.UI.LiteralControl) 
      {
        this.Text = ((System.Web.UI.LiteralControl)obj).Text;
      }
      else 
      {
        throw new System.Web.HttpException("You cannot have a child control of type " + obj.GetType().Name.ToString());
      }
    }
  }
}

Imports System.Web
Imports System.Security.Permissions

Namespace Samples.AspNet.VB.Controls
    <AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
    Public NotInheritable Class CustomTextBoxAddParsedSubObject
        Inherits System.Web.UI.WebControls.TextBox

        Protected Overrides Sub AddParsedSubObject(ByVal obj As Object)

            ' If the object is a LiteralControl, then set this control's Text property.
            If TypeOf obj Is System.Web.UI.LiteralControl Then
                Me.Text = CType(obj, System.Web.UI.LiteralControl).Text
            Else
                Throw New System.Web.HttpException("You cannot have children controls of type " + obj.GetType().Name.ToString())
            End If
        End Sub
    End Class
End Namespace

Applies to

See also