HtmlSelect.OnPreRender-Methode
Löst das PreRender-Ereignis für das HtmlSelect-Steuerelement aus.
Namespace: System.Web.UI.HtmlControls
Assembly: System.Web (in system.web.dll)
Syntax
'Declaration
Protected Friend Overrides Sub OnPreRender ( _
e As EventArgs _
)
'Usage
Dim e As EventArgs
Me.OnPreRender(e)
protected internal override void OnPreRender (
EventArgs e
)
protected public:
virtual void OnPreRender (
EventArgs^ e
) override
protected void OnPreRender (
EventArgs e
)
protected internal override function OnPreRender (
e : EventArgs
)
Parameter
- e
Ein EventArgs, das die Ereignisdaten enthält.
Hinweise
Wenn die Size-Eigenschaft größer als 1 ist, registriert die OnPreRender-Methode das HtmlSelect-Steuerelement für das Page-Steuerelement als Steuerelement, für das eine Postbackverarbeitung erforderlich ist.
Beispiel
Im folgenden Codebeispiel wird das Überschreiben der OnPreRender-Methode veranschaulicht, sodass diese die Mehrfachauswahl in einem benutzerdefinierten HtmlSelect-Serversteuerelement zulässt.
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB.Controls" Assembly="Samples.AspNet.VB" %>
<%@ Page Language="VB" AutoEventWireup="True" %>
<HTML>
<HEAD>
<title>Custom HtmlSelect - OnPreRender - VB.NET Example</title>
<script runat="server">
Sub HtmlInputButton1_ServerClick(sender As Object, e As EventArgs)
If HtmlSelect1.SelectedIndex >= 0 Then
If HtmlSelect1.Multiple = True Then
Div1.InnerHtml = "You selected:"
Dim i As Integer
For i = 0 To HtmlSelect1.Items.Count - 1
If HtmlSelect1.Items(i).Selected = True Then
Div1.InnerHtml += "<br> " & HtmlSelect1.Items(i).Value
End If
Next i
Else
Div1.InnerHtml = "You selected " & HtmlSelect1.Value
End If
Else
Div1.InnerHtml = "You did not select an item."
End If
End Sub
</script>
</HEAD>
<body>
<form id="Form1" method="post" runat="server">
<h3>Custom HtmlSelect - OnPreRender - VB.NET Example</h3>
<p>
<aspSample:CustomHtmlSelectOnPreRender
id="HtmlSelect1"
name="HtmlSelect1"
runat="server">
<OPTION value="Option1">Option1</OPTION>
<OPTION value="Option2">Option2</OPTION>
<OPTION value="Option3">Option3</OPTION>
</aspSample:CustomHtmlSelectOnPreRender>
</p>
<p>
<INPUT
id="HtmlInputButton1"
runat="server"
type="button"
onserverclick="HtmlInputButton1_ServerClick"
value="Select"
name="HtmlInputButton1">
</p>
<p>
<DIV id="Div1" runat="server"
style="DISPLAY: inline; WIDTH: 256px; HEIGHT: 15px"
ms_positioning="FlowLayout" />
</p>
</form>
</body>
</HTML>
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS.Controls" Assembly="Samples.AspNet.CS" %>
<%@ Page Language="C#" AutoEventWireup="True" %>
<HTML>
<HEAD>
<title>Custom HtmlSelect - OnPreRender - C# Example</title>
<script runat="server">
void HtmlInputButton1_ServerClick(Object sender, EventArgs e)
{
if (HtmlSelect1.SelectedIndex >= 0)
{
if (HtmlSelect1.Multiple == true)
{
Div1.InnerHtml = "You selected:";
for (int i=0; i<=HtmlSelect1.Items.Count - 1; i++)
{
if (HtmlSelect1.Items[i].Selected == true)
{
Div1.InnerHtml += "<br> " + HtmlSelect1.Items[i].Value;
}
}
}
else
{
Div1.InnerHtml = "You selected " + HtmlSelect1.Value;
}
}
else
{
Div1.InnerHtml = "You did not select an item.";
}
}
</script>
</HEAD>
<body>
<form id="Form1" method="post" runat="server">
<h3>Custom HtmlSelect - OnPreRender - C# Example</h3>
<p>
<aspSample:CustomHtmlSelectOnPreRender
id="HtmlSelect1"
name="HtmlSelect1"
runat="server">
<OPTION value="Option1">Option1</OPTION>
<OPTION value="Option2">Option2</OPTION>
<OPTION value="Option3">Option3</OPTION>
</aspSample:CustomHtmlSelectOnPreRender>
</p>
<p>
<INPUT
id="HtmlInputButton1"
runat="server"
type="button"
onserverclick="HtmlInputButton1_ServerClick"
value="Select"
name="HtmlInputButton1">
</p>
<p>
<DIV id="Div1" runat="server"
style="DISPLAY: inline; WIDTH: 256px; HEIGHT: 15px"
ms_positioning="FlowLayout" />
</p>
</form>
</body>
</HTML>
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.JSl.Controls" Assembly="Samples.AspNet.JSL" %>
<%@ Page Language="VJ#" AutoEventWireup="True" %>
<HTML>
<HEAD>
<title>Custom HtmlSelect - OnPreRender - 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 - OnPreRender - VJ# Example</h3>
<p>
<aspSample:CustomHtmlSelectOnPreRender
id="HtmlSelect1"
name="HtmlSelect1"
runat="server">
<OPTION value="Option1">Option1</OPTION>
<OPTION value="Option2">Option2</OPTION>
<OPTION value="Option3">Option3</OPTION>
</aspSample:CustomHtmlSelectOnPreRender>
</p>
<p>
<INPUT
id="HtmlInputButton1"
runat="server"
type="button"
onserverclick="HtmlInputButton1_ServerClick"
value="Select"
name="HtmlInputButton1">
</p>
<p>
<DIV id="Div1" runat="server"
style="DISPLAY: inline; WIDTH: 256px; HEIGHT: 15px"
ms_positioning="FlowLayout" />
</p>
</form>
</body>
</HTML>
<AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
Public NotInheritable Class CustomHtmlSelectOnPreRender
Inherits System.Web.UI.HtmlControls.HtmlSelect
Protected Overrides Sub OnPreRender(ByVal e As System.EventArgs)
' Call the base's OnPreRender method.
MyBase.OnPreRender(e)
' Allow multiple selections.
Me.Multiple = True
End Sub
End Class
using System.Web;
using System.Security.Permissions;
namespace Samples.AspNet.CS.Controls
{
[AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
public sealed class CustomHtmlSelectOnPreRender : System.Web.UI.HtmlControls.HtmlSelect
{
protected override void OnPreRender(System.EventArgs e)
{
// Call the base's OnPreRender method.
base.OnPreRender(e);
// Allow multiple selections.
this.Multiple = true;
}
}
}
package Samples.AspNet.JSL.Controls;
public class CustomHtmlSelectOnPreRender
extends System.Web.UI.HtmlControls.HtmlSelect
{
protected void OnPreRender(System.EventArgs e)
{
// Call the base's OnPreRender method.
super.OnPreRender(e);
// Allow multiple selections.
this.set_Multiple(true);
} //OnPreRender
} //CustomHtmlSelectOnPreRender
Plattformen
Windows 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.
Versionsinformationen
.NET Framework
Unterstützt in: 2.0, 1.1, 1.0
Siehe auch
Referenz
HtmlSelect-Klasse
HtmlSelect-Member
System.Web.UI.HtmlControls-Namespace
Size
RegisterRequiresPostBack