INamingContainer Interface

Identifies a container control that creates a new ID namespace within a Page object's control hierarchy. This is a marker interface only.

Namespace:   System.Web.UI
Assembly:  System.Web (in System.Web.dll)

public interface INamingContainer
public interface class INamingContainer
type INamingContainer = interface end
Public Interface INamingContainer

Any control that implements this interface creates a new namespace in which all child control ID attributes are guaranteed to be unique within an entire application. The marker provided by this interface allows unique naming of the dynamically generated server control instances within the Web server controls that support data binding. These controls include the Repeater, DataGrid, DataList, CheckBoxList, ChangePassword, LoginView, Menu, SiteMapNodeItem, and RadioButtonList controls.

When you develop templated controls, you should implement this interface to avoid naming conflicts on a page. For more information, see ASP.NET Control Designers Overview.


The following code example demonstrates a templated custom server control that implements the INamingContainer interface. When this custom server control is used in an .aspx file, it will provide a unique namespace for any server controls that it contains.

using System;
using System.Collections;
using System.Web;
using System.Web.UI;

namespace TemplateControlSamples {

    public class RepeaterItem : Control, INamingContainer {

        private int itemIndex;
        private object dataItem;

        public RepeaterItem(int itemIndex, object dataItem) {
            this.itemIndex = itemIndex;
            this.dataItem = dataItem;

        public object DataItem {
            get {
                return dataItem;

        public int ItemIndex {
            get {
                return itemIndex;
Imports System
Imports System.Collections
Imports System.Web
Imports System.Web.UI

Namespace TemplateControlSamplesVB

    Public Class RepeaterItemVB : Inherits Control : Implements INamingContainer

        Private _ItemIndex As Integer
        Private _DataItem As Object

        Public Sub New(ItemIndex As Integer, DataItem As Object)
            _ItemIndex = ItemIndex
            _DataItem = DataItem
        End Sub

        Public ReadOnly Property DataItem As Object
                return _DataItem
            End Get
        End Property

        Public ReadOnly Property ItemIndex As Integer
                return _ItemIndex
            End Get
        End Property

    End Class

End Namespace
Version Information
.NET Framework
Available since 1.1
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