Control.ChildControlsCreated Control.ChildControlsCreated Control.ChildControlsCreated Control.ChildControlsCreated Property

Definizione

Ottiene un valore che indica se i controlli figli del controllo server sono stati creati.Gets a value that indicates whether the server control's child controls have been created.

protected:
 property bool ChildControlsCreated { bool get(); void set(bool value); };
protected bool ChildControlsCreated { get; set; }
member this.ChildControlsCreated : bool with get, set
Protected Property ChildControlsCreated As Boolean

Valore della proprietà

true se i controlli figli sono stati creati; in caso contrario, false.true if child controls have been created; otherwise, false.

Esempi

Nell'esempio seguente viene illustrato un override del OnDataBinding metodo di un controllo Repeater personalizzato.The following example demonstrates an override of the OnDataBinding method of a custom Repeater control. Per assicurarsi che i controlli figlio non vengano creati fino a quando non si ChildControlsCreated verifica di nuovo data binding true , la RepeaterItem proprietà viene impostata su dopo che gli oggetti ControlCollection sono stati creati e aggiunti all'oggetto del controllo.To ensure that child controls are not created until data binding occurs again, the ChildControlsCreated property is set to true after the RepeaterItem objects are created and added to the control's ControlCollection object.

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 utilizzare il controllo Repeater personalizzato in una pagina Web.The following example demonstrates how to use the custom repeater control in a Web page.

<%@ 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>

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