HtmlInputRadioButton.OnPreRender(EventArgs) Method

Reference

Definition

Namespace:: System.Web.UI.HtmlControls

Assembly:: System.Web.dll

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

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

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

A EventArgs that contains the event data.

Examples

The following code example demonstrates how to override the OnPreRender method so that it adds a Title attribute in a custom HtmlInputRadioButton server control.

<%@ Page Language="C#" AutoEventWireup="True" %>
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS.Controls" Assembly="Samples.AspNet.CS" %>
<!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 HtmlInputRadioButton - OnPreRender - C# Example</title>
    <script runat="server">
      void Page_Load(Object sender, EventArgs e) 
      {
        Div1.InnerHtml = "";
      }

      void HtmlInputRadioButtonGroup1_ServerChange(object sender, System.EventArgs e)
      {
        // Diplay the value of the selected HtmlInputRadioButton control.
        System.Web.UI.HtmlControls.HtmlInputRadioButton htmlInputRadioButtonGroup1 = (System.Web.UI.HtmlControls.HtmlInputRadioButton) sender;
        Div1.InnerHtml = "You change your selection to: " + htmlInputRadioButtonGroup1.Value;
      }
    </script>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">
      <h3>Custom HtmlInputRadioButton - OnPreRender - C# Example</h3>

      <aspSample:CustomHtmlInputRadioButtonOnPreRender 
        id="HtmlInputRadioButton1" 
        name="HtmlInputRadioButtonGroup1" 
        runat="server" 
        type="radio" checked
        onserverchange="HtmlInputRadioButtonGroup1_ServerChange" 
        value="HtmlInputRadioButton1">HtmlInputRadioButton1
      </aspSample:CustomHtmlInputRadioButtonOnPreRender>
      <br />

      <aspSample:CustomHtmlInputRadioButtonOnPreRender 
        id="HtmlInputRadioButton2" 
        name="HtmlInputRadioButtonGroup1" 
        runat="server" 
        type="radio" 
        onserverchange="HtmlInputRadioButtonGroup1_ServerChange" 
        value="HtmlInputRadioButton2">HtmlInputRadioButton2
      </aspSample:CustomHtmlInputRadioButtonOnPreRender>

      <p>
        <input type="submit" value="Submit" id="Submit1" name="Submit1" runat="server" />
      </p>
      
      <div 
        id="Div1" 
        runat="server" 
        style="DISPLAY: inline; WIDTH: 256px; HEIGHT: 15px" />
    </form>
  </body>
</html>

<%@ Page Language="VB" AutoEventWireup="True" %>
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB.Controls" Assembly="Samples.AspNet.VB" %>
<!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 HtmlInputRadioButton - OnPreRender - Visual Basic Example</title>
    <script runat="server">
      Sub Page_Load(sender As Object, e As EventArgs)
        Div1.InnerHtml = ""
      End Sub

      Sub HtmlInputRadioButtonGroup1_ServerChange(sender As Object, e As System.EventArgs)
        Dim htmlInputRadioButtonGroup1 As System.Web.UI.HtmlControls.HtmlInputRadioButton  = CType(sender, System.Web.UI.HtmlControls.HtmlInputRadioButton)
        Div1.InnerHtml = "You change your selection to: " & htmlInputRadioButtonGroup1.Value
      End Sub
    </script>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">
      <h3>Custom HtmlInputRadioButton - OnPreRender - Visual Basic Example</h3>

      <aspSample:CustomHtmlInputRadioButtonOnPreRender 
        id="HtmlInputRadioButton1" 
        name="HtmlInputRadioButtonGroup1" 
        runat="server" 
        type="radio" checked
        onserverchange="HtmlInputRadioButtonGroup1_ServerChange" 
        value="HtmlInputRadioButton1">HtmlInputRadioButton1
      </aspSample:CustomHtmlInputRadioButtonOnPreRender>
      <br />

      <aspSample:CustomHtmlInputRadioButtonOnPreRender 
        id="HtmlInputRadioButton2" 
        name="HtmlInputRadioButtonGroup1" 
        runat="server" 
        type="radio" 
        onserverchange="HtmlInputRadioButtonGroup1_ServerChange" 
        value="HtmlInputRadioButton2">HtmlInputRadioButton2
      </aspSample:CustomHtmlInputRadioButtonOnPreRender>

      <p>
        <input type="submit" value="Submit" id="Submit1" name="Submit1" runat="server" />
      </p>
      
      <div 
        id="Div1" 
        runat="server" 
        style="DISPLAY: inline; WIDTH: 256px; HEIGHT: 15px" />
    </form>
  </body>
</html>

using System.Web;
using System.Security.Permissions;
namespace Samples.AspNet.CS.Controls
{
    [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
    public sealed class CustomHtmlInputRadioButtonOnPreRender : System.Web.UI.HtmlControls.HtmlInputRadioButton
    {
        protected override void OnPreRender(System.EventArgs e)
        {
            // Run the OnPreRender method on the base class.
            base.OnPreRender(e);
            
            // Add a Title attribute.
            this.Attributes.Add("title", "Option " + this.Value);
        }
    }
}

<AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
Public NotInheritable Class CustomHtmlInputRadioButtonOnPreRender
    Inherits System.Web.UI.HtmlControls.HtmlInputRadioButton

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

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

        ' Add a Title attribute.
        Me.Attributes.Add("title", "Option " + Me.Value)
    End Sub
End Class

Remarks

The OnPreRender method is called just prior to rendering the HtmlInputRadioButton control.

The OnPreRender method is used primarily by control developers extending the functionality of the HtmlInputRadioButton control.

Applies to

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