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HtmlInputRadioButton.ServerChange Event

  • Reference

Definition

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

Occurs when the value of the Checked property of the HtmlInputRadioButton control changes between posts to the server.

C# 
public event EventHandler ServerChange;

Event Type

EventHandler

Examples

The following code example demonstrates how to specify and code a handler for the ServerChange event. The custom event handler updates a label on the Web page to display the value of the selected radio button.

ASP.NET (C#) 
<%@ 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>HtmlInputRadioButton Sample</title>
<script runat="server">

      void Server_Change(object sender, EventArgs e) 
      {
         if (Radio1.Checked)
            Span1.InnerHtml = "You selected " +
                              Radio1.Value;
         else if (Radio2.Checked)
            Span1.InnerHtml = "You selected " +
                              Radio2.Value;
         else if (Radio3.Checked)
            Span1.InnerHtml = "You selected " +
                              Radio3.Value;
      }
         

   </script>

</head>

<body>

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

      <h3>HtmlInputRadioButton Sample</h3>

      <input type="radio" 
             id="Radio1" 
             name="Mode"
             value="Radio Button 1"
             onserverchange="Server_Change" 
             runat="server"/>
      Option 1
      <br />

      <input type="radio" 
             id="Radio2" 
             name="Mode"
             value="Radio Button 2"
             onserverchange="Server_Change" 
             runat="server"/>
      Option 2
      <br />

      <input type="radio" 
             id="Radio3" 
             name="Mode"
             value="Radio Button 3"
             onserverchange="Server_Change" 
             runat="server"/>
      Option 3

      <br />

      <input type="submit" 
             id="Button1" 
             value="Submit" 
             runat="server"/>

      <br />

      <span id="Span1" 
            runat="server" />

   </form>

</body>
</html>
ASP.NET (C#) 

<%@ 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>HtmlInputRadioButton ServerChange Example</title>
<script runat="server">

      void Server_Change(object sender, EventArgs e) 
      {
         if (Radio1.Checked)
         {
            Span1.InnerHtml = "You selected " + Radio1.Value;
         }
         else if (Radio2.Checked)
         {
            Span1.InnerHtml = "You selected " + Radio2.Value;
         }
         else if (Radio3.Checked)
         {
            Span1.InnerHtml = "You selected " + Radio3.Value;
         }
      }

      void Page_Load(object sender, EventArgs e)
      {
         // Create an EventHandler delegate for the method you want to
         // handle the event, and then add it to the list of methods
         // called when the event is raised.
         Radio1.ServerChange += new System.EventHandler(this.Server_Change);
         Radio2.ServerChange += new System.EventHandler(this.Server_Change);
         Radio3.ServerChange += new System.EventHandler(this.Server_Change);
      }         

   </script>

</head>

<body>

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

      <h3>HtmlInputRadioButton ServerChange Example</h3>

      <input type="radio" 
             id="Radio1" 
             name="Mode"
             value="Radio Button 1"
             runat="server"/>
      Option 1
      <br />

      <input type="radio" 
             id="Radio2" 
             name="Mode"
             value="Radio Button 2"
             runat="server"/>
      Option 2
      <br />

      <input type="radio" 
             id="Radio3" 
             name="Mode"
             value="Radio Button 3"
             runat="server"/>
      Option 3

      <br />

      <input type="submit" 
             id="Button1" 
             value="Submit" 
             runat="server"/>

      <br />

      <span id="Span1" 
            runat="server" />

   </form>

</body>
</html>

Remarks

The ServerChange event is raised when the Checked property of the HtmlInputRadioButton control changes value between posts to the server. This allows you to create a custom event handler that performs a specific set of instructions (such as data validation) when the event is raised.

Note

The control must have view state enabled for the ServerChange event to work correctly. To enable view state for all controls on the Web Forms page, set the Page.EnableViewState property to true. You can also enable view state for an individual control by setting the Control.EnableViewState property to true.

For more information about how to handle events, see Handling and Raising Events.

Applies to

Product Versions
.NET Framework 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1

See also