使用 NamingContainer 屬性決定控制項的命名容器
更新：2007 年 11 月
您可以藉由 NamingContainer 屬性逐步查核網頁上的控制項樹狀結構。與 Container 關鍵字 (只能用於內嵌程式碼，也就是在宣告式 <%# %> 運算式中) 相比，在程式碼中類別或衍生類別的任何執行個體 (Instance) 都可以使用 NamingContainer 屬性。
下列程式碼範例說明如何查核 ASP.NET Web 網頁的控制項樹狀結構。按鈕的 ChangeBtn_Click 方法處理常式會使用 FindControl 方法，在 Repeater 控制項的第一個項目中搜尋名為 Message 的控制項，然後判斷該控制項的 NamingContainer 物件。然後再判斷首次呼叫 NamingContainer 屬性所傳回控制項的命名容器，並且繼續在控制項樹狀結構中執行這個動作，直到找到沒有命名容器的控制項為止 (請注意，WalkContainers 方法也會在最底層加入控制項型別，其本身不是命名容器)。
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="head1" >
<title>NamingContainer Example</title>
</head>
<script language="vb" >
Dim list As ArrayList
Private Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
list = New ArrayList
list.Add("One")
list.Add("Two")
list.Add("Three")
MyRepeater.DataSource = list
MyRepeater.DataBind()
End Sub
Private Sub ChangeBtn_Click(ByVal sender As Object, ByVal e As EventArgs)
Dim x As Control = MyRepeater.Items(0).FindControl("Message")
If Not x Is Nothing Then
list = WalkContainers(x)
End If
MyRepeater.DataSource = list
MyRepeater.DataBind()
End Sub
Private Function WalkContainers(ByVal ctl As Control) As ArrayList
Dim ret As New ArrayList
Dim parent As Control = ctl.NamingContainer
If Not parent Is Nothing Then
Dim sublist As ArrayList = WalkContainers(parent)
Dim j As Integer
For j = 0 To sublist.Count - 1
ret.Add(sublist(j))
Next
End If
ret.Add(ctl.GetType.Name)
Return ret
End Function
</script>
<body>
<form id="repeaterform" >
<h3>Using the NamingContainer Property to Determine a
Control's Naming Container
</h3>
<table id="mytable" width="80%">
<asp:repeater id="MyRepeater" >
<ItemTemplate>
<tr>
<td align="center" style="width:100%;">
<span id="message" >
<%#Container.DataItem%>
</span>
</td>
</tr>
</ItemTemplate>
</asp:repeater>
<tr>
<td align="center" style="width:100%;">
<input id="changebtn"
type="submit"
onserverclick="changebtn_click "
/>
</td>
</tr>
</table>
</form>
</body>
</html>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="head1" >
<title>NamingContainer Example</title>
</head>
<script language="c#" >
ArrayList list;
private void Page_Load(object sender, EventArgs e)
{
list = new ArrayList();
list.Add("One");
list.Add("Two");
list.Add("Three");
MyRepeater.DataSource = list;
MyRepeater.DataBind();
}
private void ChangeBtn_Click(object sender, EventArgs e)
{
Control x = MyRepeater.Items[0].FindControl("Message");
if (x != null) list = WalkContainers(x);
MyRepeater.DataSource = list;
MyRepeater.DataBind();
}
private ArrayList WalkContainers(Control ctl)
{
ArrayList ret = new ArrayList();
Control parent = ctl.NamingContainer;
if (parent != null)
{
ArrayList sublist = WalkContainers(parent);
for (int j = 0; j < sublist.Count; j++) ret.Add(sublist[j]);
}
ret.Add(ctl.GetType().Name);
return ret;
}
</script>
<body>
<form id="repeaterform" >
<h3>Using the NamingContainer Property to Determine a
Control's Naming Container
</h3>
<table id="mytable" width="80%">
<asp:repeater id="MyRepeater" >
<ItemTemplate>
<tr>
<td align="center" style="width:100%;">
<span id="message" >
<%#Container.DataItem%>
</span>
</td>
</tr>
</ItemTemplate>
</asp:repeater>
<tr>
<td align="center" style="width:100%;">
<input id="changebtn"
type="submit"
onserverclick="ChangeBtn_Click"
/>
</td>
</tr>
</table>
</form>
</body>
</html>