HtmlSelect.ServerChange-Ereignis
Tritt ein, wenn sich die im HtmlSelect-Steuerelement ausgewählten Elemente zwischen Bereitstellungen auf dem Server ändern.
Namespace: System.Web.UI.HtmlControls
Assembly: System.Web (in system.web.dll)
Syntax
'Declaration
Public Event ServerChange As EventHandler
'Usage
Dim instance As HtmlSelect
Dim handler As EventHandler
AddHandler instance.ServerChange, handler
public event EventHandler ServerChange
public:
event EventHandler^ ServerChange {
void add (EventHandler^ value);
void remove (EventHandler^ value);
}
/** @event */
public void add_ServerChange (EventHandler value)
/** @event */
public void remove_ServerChange (EventHandler value)
JScript unterstützt die Verwendung von Ereignissen, aber nicht die Deklaration von neuen Ereignissen.
Hinweise
Das ServerChange-Ereignis wird ausgelöst, wenn sich die ausgewählten Elemente im HtmlSelect-Steuerelement zwischen Bereitstellungen auf dem Server ändern.
Hinweis
Der Ansichtszustand für das Steuerelement muss aktiviert sein, damit das ServerChange-Ereignis ordnungsgemäß funktioniert.
Weitere Informationen über die Behandlung von Ereignissen finden Sie unter Behandeln von Ereignissen.
Beispiel
Im folgenden Codebeispiel wird veranschaulicht, wie ein Ereignishandler für das ServerChange-Ereignis des HtmlSelect-Steuerelements deklarativ angegeben und codiert wird. Der Ereignishandler bestimmt, ob die ausgewählten Elemente miteinander kompatibel sind.
<%@ Page Language="VB" AutoEventWireup="True" %>
<html>
<head>
<script runat="server">
Sub Button_Click (sender As Object, e As EventArgs)
Dim i As Integer
Label1.Text = "You selected:"
For i = 0 to Select1.Items.Count - 1
If Select1.Items(i).Selected Then
Label1.Text = Label1.Text & "<br> -" & Select1.Items(i).Text
End If
Next i
End Sub
Sub Server_Change (sender As Object, e As EventArgs)
Dim i As Integer
Dim Count As Integer = 0
For i = 0 to Select1.Items.Count - 1
If Select1.Items(i).Selected Then
Count = Count + 1
End If
Next i
If Count > 1 And Select1.Items(0).Selected Then
Label2.Text = "Hey! You can't select 'All' with another selection!!"
Else
Label2.Text = ""
End If
End Sub
</script>
</head>
<body>
<form runat="server">
<h3> HtmlSelect Example </h3>
Select items from the list: <br><br>
<select id="Select1"
Multiple="True"
OnServerChange="Server_Change"
runat="server">
<option value="All"> All </option>
<option value="1" Selected="True"> Item 1 </option>
<option value="2"> Item 2 </option>
<option value="3"> Item 3 </option>
<option value="4"> Item 4 </option>
<option value="5"> Item 5 </option>
<option value="6"> Item 6 </option>
</select>
<br><br>
<button id="Button1"
OnServerClick="Button_Click"
runat="server">
Submit
</button>
<br><br>
<asp:Label id="Label1"
runat="server"/>
<br>
<asp:Label id="Label2"
runat="server"/>
</form>
</body>
</html>
<%@ Page Language="C#" AutoEventWireup="True" %>
<html>
<head>
<script runat="server">
void Button_Click (Object sender, EventArgs e)
{
Label1.Text = "You selected:";
for (int i=0; i<=Select1.Items.Count - 1; i++)
{
if (Select1.Items[i].Selected)
Label1.Text += "<br> -" + Select1.Items[i].Text;
}
}
void Server_Change (Object sender, EventArgs e)
{
int Count = 0;
for (int i=0; i<=Select1.Items.Count - 1; i++)
{
if (Select1.Items[i].Selected)
Count++;
}
if ((Count > 1) && (Select1.Items[0].Selected))
Label2.Text = "Hey! You can't select 'All' with another selection!!";
else
Label2.Text = "";
}
</script>
</head>
<body>
<form runat="server">
<h3> HtmlSelect Example </h3>
Select items from the list: <br><br>
<select id="Select1"
Multiple="True"
OnServerChange="Server_Change"
runat="server">
<option value="All"> All </option>
<option value="1" Selected="True"> Item 1 </option>
<option value="2"> Item 2 </option>
<option value="3"> Item 3 </option>
<option value="4"> Item 4 </option>
<option value="5"> Item 5 </option>
<option value="6"> Item 6 </option>
</select>
<br><br>
<button id="Button1"
OnServerClick="Button_Click"
runat="server">
Submit
</button>
<br><br>
<asp:Label id="Label1"
runat="server"/>
<br>
<asp:Label id="Label2"
runat="server"/>
</form>
</body>
</html>
<%@ Page Language="JScript" AutoEventWireup="True" %>
<html>
<head>
<script runat="server">
function Button_Click (sender : Object, e : EventArgs) : void
{
Label1.Text = "You selected:";
for (var i : int =0; i<=Select1.Items.Count - 1; i++)
{
if (Select1.Items[i].Selected)
Label1.Text += "<br> -" + Select1.Items[i].Text;
}
}
function Server_Change (sender : Object, e : EventArgs) : void
{
var Count : int = 0;
for (var i : int =0; i<=Select1.Items.Count - 1; i++)
{
if (Select1.Items[i].Selected)
Count++;
}
if ((Count > 1) && (Select1.Items[0].Selected))
Label2.Text = "Hey! You can't select 'All' with another selection!!";
else
Label2.Text = "";
}
</script>
</head>
<body>
<form runat="server">
<h3> HtmlSelect Example </h3>
Select items from the list: <br><br>
<select id="Select1"
Multiple="True"
OnServerChange="Server_Change"
runat="server">
<option value="All"> All </option>
<option value="1" Selected="True"> Item 1 </option>
<option value="2"> Item 2 </option>
<option value="3"> Item 3 </option>
<option value="4"> Item 4 </option>
<option value="5"> Item 5 </option>
<option value="6"> Item 6 </option>
</select>
<br><br>
<button id="Button1"
OnServerClick="Button_Click"
runat="server">
Submit
</button>
<br><br>
<asp:Label id="Label1"
runat="server"/>
<br>
<asp:Label id="Label2"
runat="server"/>
</form>
</body>
</html>
Im folgenden Codebeispiel wird veranschaulicht, wie ein Ereignishandler für das ServerChange-Ereignis des HtmlSelect-Steuerelements programmgesteuert angegeben und codiert wird. Der Ereignishandler bestimmt, ob die ausgewählten Elemente miteinander kompatibel sind.
<%@ Page Language="VB" AutoEventWireup="True" %>
<html>
<head>
<script runat="server">
Sub Button_Click (sender As Object, e As EventArgs)
' Display the selected items.
Label1.Text = "You selected:"
Dim i As Integer
For i=0 To Select1.Items.Count - 1
If Select1.Items(i).Selected Then
Label1.Text &= "<br> -" & Select1.Items(i).Text
End If
Next i
End Sub
Sub Server_Change(sender As Object, e As EventArgs)
' The ServerChange event is commonly used for data validation.
' This method will display a warning if the "All" option is
' selected in combination with another item in the list.
Dim Count As Integer = 0
Dim i As Integer
' Determine the number of selected items in the list.
For i=0 To Select1.Items.Count - 1
If Select1.Items(i).Selected Then
Count = Count + 1
End If
Next i
' Display an error message if more than one item is selected with
' the "All" item selected.
If ((Count > 1) And (Select1.Items(0).Selected)) Then
Label2.Text = "Hey! You can't select 'All' with another selection!!"
Else
Label2.Text = ""
End If
End Sub
Sub Page_Load(sender As Object, e As EventArgs)
' 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.
AddHandler Select1.ServerChange, AddressOf Server_Change
AddHandler Button1.ServerClick, AddressOf Button_Click
End Sub
</script>
</head>
<body>
<form runat="server">
<h3> HtmlSelect ServerChange Example </h3>
Select items from the list: <br><br>
<select id="Select1"
Multiple="True"
runat="server">
<option value="All"> All </option>
<option value="1" Selected="True"> Item 1 </option>
<option value="2"> Item 2 </option>
<option value="3"> Item 3 </option>
<option value="4"> Item 4 </option>
<option value="5"> Item 5 </option>
<option value="6"> Item 6 </option>
</select>
<br><br>
<button id="Button1"
runat="server">
Submit
</button>
<br><br>
<asp:Label id="Label1"
runat="server"/>
<br>
<asp:Label id="Label2"
runat="server"/>
</form>
</body>
</html>
<%@ Page Language="C#" AutoEventWireup="True" %>
<html>
<head>
<script runat="server">
void Button_Click (Object sender, EventArgs e)
{
// Display the selected items.
Label1.Text = "You selected:";
for (int i=0; i<=Select1.Items.Count - 1; i++)
{
if (Select1.Items[i].Selected)
Label1.Text += "<br> -" + Select1.Items[i].Text;
}
}
void Server_Change(Object sender, EventArgs e)
{
// The ServerChange event is commonly used for data validation.
// This method will display a warning if the "All" option is
// selected in combination with another item in the list.
int Count = 0;
// Determine the number of selected items in the list.
for (int i=0; i<=Select1.Items.Count - 1; i++)
{
if (Select1.Items[i].Selected)
Count++;
}
// Display an error message if more than one item is selected with
// the "All" item selected.
if ((Count > 1) && (Select1.Items[0].Selected))
{
Label2.Text = "Hey! You can't select 'All' with another selection!!";
}
else
{
Label2.Text = "";
}
}
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.
Select1.ServerChange += new System.EventHandler(this.Server_Change);
Button1.ServerClick += new System.EventHandler(this.Button_Click);
}
</script>
</head>
<body>
<form runat="server">
<h3> HtmlSelect Server Change Example </h3>
Select items from the list: <br><br>
<select id="Select1"
Multiple="True"
runat="server">
<option value="All"> All </option>
<option value="1" Selected="True"> Item 1 </option>
<option value="2"> Item 2 </option>
<option value="3"> Item 3 </option>
<option value="4"> Item 4 </option>
<option value="5"> Item 5 </option>
<option value="6"> Item 6 </option>
</select>
<br><br>
<button id="Button1"
runat="server">
Submit
</button>
<br><br>
<asp:Label id="Label1"
runat="server"/>
<br>
<asp:Label id="Label2"
runat="server"/>
</form>
</body>
</html>
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
OnServerChange
System.EventHandler