Control.ChildControlsCreated Proprietà
Importante
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Ottiene un valore che indica se i controlli figli del controllo server sono stati creati.
protected:
property bool ChildControlsCreated { bool get(); void set(bool value); };C#
protected bool ChildControlsCreated { get; set; }member this.ChildControlsCreated : bool with get, setProtected Property ChildControlsCreated As Booleantrue se i controlli figli sono stati creati; in caso contrario, false.
Nell'esempio OnDataBinding seguente viene illustrato un override del metodo di un controllo personalizzato Repeater . Per assicurarsi che i controlli figlio non vengano creati fino a quando il data binding non si verifica di nuovo, la ChildControlsCreated proprietà viene impostata su true dopo la RepeaterItem creazione degli oggetti e l'aggiunta all'oggetto del ControlCollection controllo.
C#
using System;
using System.Collections;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace TemplateControlSamples
{
[ParseChildren(true)]
public class CustomRepeater : Repeater
{
// Override to prevent LiteralControls from being added as children.
protected override void AddParsedSubObject(object o)
{
}
// Override to create repeated items.
protected override void CreateChildControls()
{
object o = ViewState["NumItems"];
if (o != null)
{
// Clear any existing child controls.
Controls.Clear();
int numItems = (int)o;
for (int i = 0; i < numItems; i++)
{
// Create an item.
RepeaterItem item = new RepeaterItem(i, ListItemType.Item);
// Initialize the item from the template.
ItemTemplate.InstantiateIn(item);
// Add the item to the ControlCollection.
Controls.Add(item);
}
}
}
// Override to create the repeated items from the DataSource.
protected override void OnDataBinding(EventArgs e)
{
base.OnDataBinding(e);
if (DataSource != null)
{
// Iterate over an ICollection DataSource, creating a new item for each data item.
IEnumerator dataEnum = ((ICollection)base.DataSource).GetEnumerator();
int i = 0;
while (dataEnum.MoveNext())
{
// Create an item.
RepeaterItem item = new RepeaterItem(i, ListItemType.Item);
item.DataItem = dataEnum.Current;
// Initialize the item from the template.
ItemTemplate.InstantiateIn(this);
// Add the item to the ControlCollection.
Controls.Add(item);
i++;
}
// Prevent child controls from being created again.
ChildControlsCreated = true;
// Store the number of items created in view state for postback scenarios.
ViewState["NumItems"] = i;
}
}
}
}
Imports System.Collections
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls
Namespace TemplateControlSamplesVB
<ParseChildren(True)> _
Public Class CustomRepeaterVB : Inherits Repeater
' Override to prevent LiteralControls from being added as children.
Protected Overrides Sub AddParsedSubObject(ByVal O As Object)
End Sub
' Override to create repeated items.
Protected Overrides Sub CreateChildControls()
Dim O As Object = ViewState("NumItems")
If Not (O Is Nothing) Then
' Clear any existing child controls.
Controls.Clear()
Dim i As Integer
Dim NumItems As Integer = CInt(O)
For i = 0 To NumItems - 1
' Create an item.
Dim Item As RepeaterItem = New RepeaterItem(i, ListItemType.Item)
' Initialize the item from the template.
ItemTemplate.InstantiateIn(Item)
' Add the item to the ControlCollection.
Controls.Add(Item)
Next
End If
End Sub
' Override to create the repeated items from the DataSource.
Protected Overrides Sub OnDataBinding(ByVal E As EventArgs)
MyBase.OnDataBinding(E)
If Not DataSource Is Nothing Then
' Iterate over the DataSource, creating a new item for each data item.
Dim DataEnum As IEnumerator = DataSource.GetEnumerator()
Dim i As Integer = 0
Do While (DataEnum.MoveNext())
' Create an item.
Dim Item As RepeaterItem = New RepeaterItem(i, ListItemType.Item)
' Initialize the item from the template.
ItemTemplate.InstantiateIn(Item)
' Add the item to the ControlCollection.
Controls.Add(Item)
i = i + 1
Loop
' Prevent child controls from being created again.
ChildControlsCreated = True
' Store the number of items created in view state for postback scenarios.
ViewState("NumItems") = i
End If
End Sub
End Class
End Namespace
Nell'esempio seguente viene illustrato come usare il controllo ripetitore personalizzato in una pagina Web.
ASP.NET (C#)
<%@ Page Language="C#" %>
<%@ Register TagPrefix="Samples" Namespace="TemplateControlSamples" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
protected void Page_Load(object sender, EventArgs e)
{
ArrayList a = new ArrayList();
a.Add("data item 1");
a.Add("data item 2");
Repeater1.DataSource = a;
Page.DataBind();
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>ChildControlsCreated Example</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<Samples:CustomRepeater ID="Repeater1" runat="server">
<ItemTemplate><%# Container.DataItem %> <br /></ItemTemplate>
</Samples:CustomRepeater>
</div>
</form>
</body>
</html>
<%@ Page Language="VB" %>
<%@ Register TagPrefix="Samples" Namespace="TemplateControlSamplesVB" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)
Dim a As New ArrayList()
a.Add("data item 1")
a.Add("data item 2")
Repeater1.DataSource = a
Page.DataBind()
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>ChildControlsCreated Example</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<Samples:CustomRepeaterVB ID="Repeater1" runat="server">
<ItemTemplate><%# Container.DataItem %> <br /></ItemTemplate>
</Samples:CustomRepeaterVB>
</div>
</form>
</body>
</html>
| Prodotto | Versioni |
|---|---|
| .NET Framework | 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8 |