HtmlSelect.RenderChildren Method
.NET Framework 3.0
Renders the HtmlSelect control's child controls to the specified HtmlTextWriter object.
Namespace: System.Web.UI.HtmlControls
Assembly: System.Web (in system.web.dll)
Assembly: System.Web (in system.web.dll)
protected void RenderChildren ( HtmlTextWriter writer )
protected internal override function RenderChildren ( writer : HtmlTextWriter )
Not applicable.
Parameters
- writer
The HtmlTextWriter that receives the rendered content.
| Exception type | Condition |
|---|---|
| Multiple items were selected but the Multiple property is set to false. |
The RenderChildren method overrides the base class's RenderChildren method without calling the base method. Each of the <option> elements between the opening and closing <select> tags is rendered with a value attribute, a selected attribute if the item is selected, and its associated text.
If multiple items were selected but the Multiple property is set to false, then an HttpException exception is thrown.
The following code example demonstrates how to override the RenderChildren method so that it always displays default option text in a custom HtmlSelect server control.
<%@ 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 HtmlSelect - RenderChildren - VJ# Example</title>
<script runat="server">
void HtmlInputButton1_ServerClick(Object sender, EventArgs e)
{
if (HtmlSelect1.get_SelectedIndex() >= 0) {
if (HtmlSelect1.get_Multiple() == true) {
Div1.set_InnerHtml("You selected:");
for (int i=0; i<=HtmlSelect1.get_Items().get_Count() - 1; i++) {
if (HtmlSelect1.get_Items().get_Item(i).
get_Selected() == true) {
Div1.set_InnerHtml(Div1.get_InnerHtml() + "<br /> " + HtmlSelect1.get_Items().get_Item(i).get_Value());
}
}
}
else {
Div1.set_InnerHtml("You selected " + HtmlSelect1.get_Value());
}
}
else {
Div1.set_InnerHtml("You did not select an item.");
}
} //HtmlInputButton1_ServerClick
</script>
</head>
<body>
<form id="Form1" method="post" runat="server">
<h3>Custom HtmlSelect - RenderChildren - VJ# Example</h3>
<p>
<aspSample:CustomHtmlSelectRenderChildren
id="HtmlSelect1" multiple
name="HtmlSelect1"
runat="server">
<option value="Option1">Option1</option>
<option value="Option2">Option2</option>
<option value="Option3">Option3</option>
</aspSample:CustomHtmlSelectRenderChildren>
</p>
<p>
<input
id="HtmlInputButton1"
runat="server"
type="button"
onserverclick="HtmlInputButton1_ServerClick"
value="Select"
name="HtmlInputButton1" />
</p>
<br />
<div id="Div1" runat="server"
style="DISPLAY: inline; WIDTH: 256px; HEIGHT: 15px" />
</form>
</body>
</html>
package Samples.AspNet.JSL.Controls;
public class CustomHtmlSelectRenderChildren
extends System.Web.UI.HtmlControls.HtmlSelect
{
protected void RenderChildren(System.Web.UI.HtmlTextWriter writer)
{
// Create a default OPTION.
System.Web.UI.WebControls.ListItem listItem =
new System.Web.UI.WebControls.ListItem("<Select an option> ", "");
this.get_Items().Insert(0, listItem);
// Call base's RenderChildren method.
super.RenderChildren(writer);
} //RenderChildren
} //CustomHtmlSelectRenderChildren
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