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HtmlInputCheckBox.OnPreRender Method

.NET Framework 3.0

Raises the OnPreRender event and registers the control as one that requires postback handling.

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

protected internal override void OnPreRender (
	EventArgs e
)

protected void OnPreRender (
	EventArgs e
)

JScript

protected internal override function OnPreRender (
	e : EventArgs
)

XAML

Not applicable.

Parameters

e: An EventArgs that contains event data.

Remarks

The OnPreRender method overrides the base OnPreRender method. OnPreRender is used primarily by control developers.

Example

The following code example demonstrates how to override the OnPreRender method in a custom server control so that a Title attribute is added to each HtmlInputCheckBox control.

<%@ 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 HtmlInputCheckBox - OnPreRender - C# Example</title>
    <script runat="server">
      void Button1_Click(Object sender, EventArgs e)
      {
        Div1.InnerHtml = "";

        if(HtmlInputCheckBox1.Checked == true)
        {
          Div1.InnerHtml = "You like basketball. ";
        }

        if(HtmlInputCheckBox2.Checked == true)
        {
          Div1.InnerHtml += "You like football. ";
        }

        if(HtmlInputCheckBox3.Checked == true)
        {
          Div1.InnerHtml += "You like soccer. ";
        }
      }
    </script>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">
      <h3>Custom HtmlInputCheckBox - OnPreRender - C# Example</h3>
      <br />
      Enter Interests:<p>
      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox1"
        runat="server"
        type="checkbox" checked
        value="Basketball"> Basketball

      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox2"
        runat="server"
        type="checkbox"
        value="Football"> Football

      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox3"
        runat="server"
        type="checkbox"
        value="Soccer"> Soccer
      </p>
      <p>
      <input id="Button1"
        runat="server"
        type="button"
        value="Enter"
        onserverclick="Button1_Click"
        name="Button1" />
      </p>

      <div id="Div1" runat="server"
        style="DISPLAY: inline; WIDTH: 256px; HEIGHT: 15px" />
    </form>
  </body>
</html>

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.JSL.Controls" Assembly="Samples.AspNet.JSL" %>
<%@ Page Language="VJ#" 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 HtmlInputCheckBox - OnPreRender - C# Example</title>
    <script runat="server">
    void Button1_Click(Object sender, EventArgs e)
    {
        Div1.set_InnerHtml("");
        if(HtmlInputCheckBox1.get_Checked() == true) {
            Div1.set_InnerHtml("You like basketball. ");
        }
        if(HtmlInputCheckBox2.get_Checked() == true) {
            Div1.set_InnerHtml(Div1.get_InnerHtml() + "You like football. ");
        }
        if(HtmlInputCheckBox3.get_Checked() == true) {
            Div1.set_InnerHtml(Div1.get_InnerHtml() + "You like soccer. ");
        }
    } //Button1_Click
    </script>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">
      <h3>Custom HtmlInputCheckBox - OnPreRender - VJ# Example</h3>
      <br />
      Enter Interests:<p>
      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox1"
        runat="server"
        type="checkbox" checked
        value="Basketball"> Basketball

      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox2"
        runat="server"
        type="checkbox"
        value="Football"> Football

      <aspSample:CustomHtmlInputCheckBoxOnPreRender
        id="HtmlInputCheckBox3"
        runat="server"
        type="checkbox"
        value="Soccer"> Soccer
      </p>
      <p>
      <input id="Button1"
        runat="server"
        type="button"
        value="Enter"
        onserverclick="Button1_Click"
        name="Button1" />
      </p>

      <br />
      <div id="Div1" runat="server"
        style="DISPLAY: inline; WIDTH: 256px; HEIGHT: 15px"
        ms_positioning="FlowLayout" />
    </form>
  </body>
</html>

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

namespace Samples.AspNet.CS.Controls
{
    [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
    public sealed class CustomHtmlInputCheckBoxOnPreRender : System.Web.UI.HtmlControls.HtmlInputCheckBox
    {
        protected override void OnPreRender(System.EventArgs e)
        {
            // Call the base class's OnPreRender method.
            base.OnPreRender(e);
            
            // Add a Title attribute to each HtmlInputCheckBox.
            this.Attributes.Add("title", "If you like " + this.Value + ", then select this check box.");
        }
    }
}

package Samples.AspNet.JSL.Controls;

public class CustomHtmlInputCheckBoxOnPreRender
    extends System.Web.UI.HtmlControls.HtmlInputCheckBox
{
    protected void OnPreRender(System.EventArgs e)
    {
        // Call the base class's OnPreRender method.
        super.OnPreRender(e);
        // Add a Title attribute to each HtmlInputCheckBox.
        this.get_Attributes().Add("title", "If you like " 
            + this.get_Value() + ", then select this check box.");
    } //OnPreRender
} //CustomHtmlInputCheckBoxOnPreRender

Platforms

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

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

Version Information

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

Reference

HtmlInputCheckBox Class
HtmlInputCheckBox Members
System.Web.UI.HtmlControls Namespace

Other Resources

HTML Server Controls

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