DropDownList.CreateControlCollection Methode

Definition

Namespace:
System.Web.UI.WebControls
Assembly:
System.Web.dll

Erstellt eine Sammlung zum Speichern untergeordneter Steuerelemente.

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

Gibt zurück

ControlCollection

Gibt immer ein EmptyControlCollection.

Beispiele

Im folgenden Codebeispiel wird veranschaulicht, wie die CreateControlCollection Methode in einem benutzerdefinierten Serversteuerelement überschreibt, sodass immer eine neue Instanz der EmptyControlCollection Klasse für das DropDownList Steuerelement zurückgegeben wird. Informationen zur Verwendung von benutzerdefinierten Serversteuerelementen finden Sie unter 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

Gilt für: