HtmlSelect.RenderChildren(HtmlTextWriter) Metode
Definisi
Penting
Beberapa informasi terkait produk prarilis yang dapat diubah secara signifikan sebelum dirilis. Microsoft tidak memberikan jaminan, tersirat maupun tersurat, sehubungan dengan informasi yang diberikan di sini.
Merender HtmlSelect kontrol turunan kontrol ke objek yang ditentukan HtmlTextWriter .
protected:
override void RenderChildren(System::Web::UI::HtmlTextWriter ^ writer);protected public:
override void RenderChildren(System::Web::UI::HtmlTextWriter ^ writer);protected override void RenderChildren(System.Web.UI.HtmlTextWriter writer);protected internal override void RenderChildren(System.Web.UI.HtmlTextWriter writer);override this.RenderChildren : System.Web.UI.HtmlTextWriter -> unitProtected Overrides Sub RenderChildren (writer As HtmlTextWriter)Protected Friend Overrides Sub RenderChildren (writer As HtmlTextWriter)Parameter
- writer
- HtmlTextWriter
HtmlTextWriter yang menerima konten yang dirender.
Pengecualian
Beberapa item dipilih tetapi Multiple properti diatur ke false.
Contoh
Contoh kode berikut menunjukkan cara mengambil alih RenderChildren metode sehingga selalu menampilkan teks opsi default dalam kontrol server kustom HtmlSelect .
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS.Controls" Assembly="Samples.AspNet.CS" %>
<%@ 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>Custom HtmlSelect - RenderChildren - C# Example</title>
<script runat="server">
void HtmlInputButton1_ServerClick(Object sender, EventArgs e)
{
if (HtmlSelect1.SelectedIndex >= 0)
{
if (HtmlSelect1.Multiple)
{
Div1.InnerHtml = "You selected:";
for (int i=0; i<=HtmlSelect1.Items.Count - 1; i++)
{
if (HtmlSelect1.Items[i].Selected)
{
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 - RenderChildren - C# 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>
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB.Controls" Assembly="Samples.AspNet.VB" %>
<%@ Page Language="VB" 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 - 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 - RenderChildren - VB.NET 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>
using System.Web;
using System.Security.Permissions;
namespace Samples.AspNet.CS.Controls
{
[AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
public sealed class CustomHtmlSelectRenderChildren : System.Web.UI.HtmlControls.HtmlSelect
{
protected override 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.Items.Insert(0, listItem);
// Call base's RenderChildren method.
base.RenderChildren(writer);
}
}
}
<AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
Public NotInheritable Class CustomHtmlSelectRenderChildren
Inherits System.Web.UI.HtmlControls.HtmlSelect
Protected Overrides Sub RenderChildren(ByVal writer As System.Web.UI.HtmlTextWriter)
' Create a default OPTION.
Dim listItem As New System.Web.UI.WebControls.ListItem("<Select an option> ", "")
Me.Items.Insert(0, listItem)
' Call base's RenderChildren method.
MyBase.RenderChildren(writer)
End Sub
End Class
Keterangan
Metode ini RenderChildren mengambil alih metode kelas RenderChildren dasar tanpa memanggil metode dasar.
<option> Setiap elemen antara tag pembuka dan penutup <select> dirender dengan value atribut, selected atribut jika item dipilih, dan teks terkait.
Jika beberapa item dipilih tetapi Multiple properti diatur ke false, maka HttpException pengecualian akan dilemparkan.
