DropDownList.CreateControlCollection DropDownList.CreateControlCollection DropDownList.CreateControlCollection DropDownList.CreateControlCollection Method

Definizione

Crea una raccolta per l'archiviazione di controlli figlio.Creates a collection to store child controls.

protected:
 override System::Web::UI::ControlCollection ^ CreateControlCollection();
protected override System.Web.UI.ControlCollection CreateControlCollection ();
override this.CreateControlCollection : unit -> System.Web.UI.ControlCollection
Protected Overrides Function CreateControlCollection () As ControlCollection

Restituisce

Esempi

Nell'esempio di codice riportato di seguito viene illustrato CreateControlCollection come eseguire l'override del metodo in un controllo server personalizzato in modo che restituisca EmptyControlCollection sempre una nuova DropDownList istanza della classe per il controllo.The following code example demonstrates how to override the CreateControlCollection method in a custom server control so that it always returns a new instance of the EmptyControlCollection class for the DropDownList control. Per informazioni sull'uso dei controlli server personalizzati, vedere Procedura dettagliata: Sviluppo e utilizzo di un controlloserver Web personalizzato.For information about using custom server controls, see Walkthrough: Developing and Using a Custom Web Server Control.

<%@ Page Language="C#" AutoEventWireup="True" %>
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS.Controls" Assembly="Samples.AspNet.CS" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
  <head>
    <title>Custom DropDownList - CreateControlCollection - C# Example</title>
    <script runat="server">
      private void Page_Load(object sender, System.EventArgs e)
      {
          DropDownList1.Items.Add(new ListItem("Item1", "Item1"));
          DropDownList1.Items.Add(new ListItem("Item2", "Item2"));
          DropDownList1.Items.Add(new ListItem("Item2", "Item2"));
      }
    </script>
  </head>
  <body>
    <form id="Form1" method="post" runat="server">
      <h3>Custom DropDownList - CreateControlCollection - C# Example</h3>

      <aspSample:CustomDropDownListCreateControlCollection
        id="DropDownList1"
        runat="server" />

    </form>
  </body>
</html>
<%@ Page Language="VB" AutoEventWireup="True" %>
<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.VB.Controls" Assembly="Samples.AspNet.VB" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
    <head>
        <title>Custom DropDownList - CreateControlCollection - VB.NET Example</title>
        <script runat="server">
            Sub Page_Load(sender As Object, e As EventArgs)
                DropDownList1.Items.Add(New ListItem("Item1", "Item1"))
                DropDownList1.Items.Add(New ListItem("Item2", "Item2"))
                DropDownList1.Items.Add(New ListItem("Item2", "Item2"))
            End Sub
        </script>
    </head>
    <body>
        <form id="Form1" method="post" runat="server">
            <h3>Custom DropDownList - CreateControlCollection - VB.NET Example</h3>
            <aspSample:CustomDropDownListCreateControlCollection id="DropDownList1" runat="server" />
        </form>
    </body>
</html>
using System.Web;
using System.Security.Permissions;

namespace Samples.AspNet.CS.Controls
{
    [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal)]
    public sealed class CustomDropDownListCreateControlCollection : System.Web.UI.WebControls.DropDownList
    {
        protected override System.Web.UI.ControlCollection CreateControlCollection()
        {
            // Return a new empty ControlCollection
            return new System.Web.UI.EmptyControlCollection(this);
        }
    }
}
Imports System.Web
Imports System.Security.Permissions

Namespace Samples.AspNet.VB.Controls
    <AspNetHostingPermission(SecurityAction.Demand, Level:=AspNetHostingPermissionLevel.Minimal)> _
    Public NotInheritable Class CustomDropDownListCreateControlCollection
        Inherits System.Web.UI.WebControls.DropDownList

        Protected Overrides Function CreateControlCollection() As System.Web.UI.ControlCollection

            ' Return a new EmptyControlCollection
            Return New System.Web.UI.EmptyControlCollection(Me)
        End Function
    End Class
End Namespace

Si applica a