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TextBox.OnPreRender(EventArgs) Method

  • Reference

Definition

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

Registers client script for generating postback events prior to rendering on the client, if AutoPostBack is true.

protected:
 override void OnPreRender(EventArgs ^ e);
protected public:
 override void OnPreRender(EventArgs ^ e);
protected override void OnPreRender (EventArgs e);
protected internal override void OnPreRender (EventArgs e);
override this.OnPreRender : EventArgs -> unit
Protected Overrides Sub OnPreRender (e As EventArgs)
Protected Friend Overrides Sub OnPreRender (e As EventArgs)

Parameters

e
EventArgs

An EventArgs that contains the event data.

Examples

The following code example demonstrates how to override the OnPreRender method so that it always displays a one-point border in a custom TextBox server control.

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 - OnPreRender - C# Example</title>
    </head>
    <body>
        <form id="Form1" method="post" runat="server">
            <h3>Custom TextBox - OnPreRender - C# Example</h3>
            
            <aspSample:CustomTextBoxOnPreRender 
              id="TextBox1" 
              runat="server">Hello World!
            </aspSample:CustomTextBoxOnPreRender>
            
        </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 - OnPreRender - VB.NET Example</title>
    </head>
    <body>
        <form id="Form1" method="post" runat="server">
            <h3>Custom TextBox - OnPreRender - VB.NET Example</h3>
            
            <aspSample:CustomTextBoxOnPreRender id="TextBox1" 
             runat="server">Hello World!</aspSample:CustomTextBoxOnPreRender>
        </form>
    </body>
</html>

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

namespace Samples.AspNet.CS.Controls
{
  [AspNetHostingPermission(SecurityAction.Demand, Level=AspNetHostingPermissionLevel.Minimal)]
  public sealed class CustomTextBoxOnPreRender : System.Web.UI.WebControls.TextBox
  {
    protected override void OnPreRender(System.EventArgs e)
    {
      // Run the OnPreRender method on the base class.
      base.OnPreRender(e);

      // Display the TextBox with a 1 point border.
      this.BorderWidth = System.Web.UI.WebControls.Unit.Point(1);
    }
  }
}

Imports System.Web
Imports System.Security.Permissions

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

        Protected Overrides Sub OnPreRender(ByVal e As System.EventArgs)

            ' Run the OnPreRender method on the base class.
            MyBase.OnPreRender(e)

            ' Display the TextBox with a 1 point border.
            Me.BorderWidth = System.Web.UI.WebControls.Unit.Point(1)
        End Sub
    End Class
End Namespace

Applies to