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

Definition

Ruft einen Wert ab, der angibt, ob die untergeordneten Steuerelemente des Serversteuerelements erstellt wurden.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

Eigenschaftswert

true, wenn die untergeordneten Steuerelemente erstellt wurden, andernfalls false.true if child controls have been created; otherwise, false.

Beispiele

Im folgenden Beispiel wird eine über OnDataBinding Schreibung der-Methode eines benutzerdefinierten Repeater Steuer Elements veranschaulicht.The following example demonstrates an override of the OnDataBinding method of a custom Repeater control. Um sicherzustellen, dass untergeordnete Steuerelemente erst erstellt werden, wenn die ChildControlsCreated Datenbindung wieder auftritt true , wird RepeaterItem die-Eigenschaft auf festgelegt, nachdem die ControlCollection Objekte erstellt und dem-Objekt des Steuer Elements hinzugefügt wurden.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

Im folgenden Beispiel wird veranschaulicht, wie das benutzerdefinierte Repeater-Steuerelement auf einer Webseite verwendet wird.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>

Gilt für:

Siehe auch