Control.ChildControlsCreated Свойство

Определение

Пространство имен:

System.Web.UI

Сборка:

System.Web.dll

Возвращает значение, которое указывает, созданы ли дочерние элементы управления серверного элемента управления.

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

Значение свойства

Boolean

true, если дочерний элемент управления был создан; в противном случае — false.

Примеры

В следующем примере показано переопределение OnDataBinding метода пользовательского Repeater элемента управления. Чтобы гарантировать, что дочерние элементы управления не создаются до повторной привязки данных, свойству ChildControlsCreated присваивается значение true после RepeaterItem создания объектов и добавления в объект элемента управления ControlCollection .

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

В следующем примере показано, как использовать пользовательский элемент управления repeater на веб-странице.

<%@ 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>

См. также раздел

• CreateChildControls()