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.NET Framework Class Library

Control.NamingContainer Property

Gets a reference to the server control's naming container, which creates a unique namespace for differentiating between server controls with the same Control.ID property value.

Namespace:  System.Web.UI
Assembly:  System.Web (in System.Web.dll)
<BrowsableAttribute(False)> _
<BindableAttribute(False)> _
Public Overridable ReadOnly Property NamingContainer As Control

Property Value

Type: System.Web.UI.Control
The server control's naming container.

Each page in an ASP.NET Web application contains a hierarchy of controls. This hierarchy is not dependent on whether a control generates UI visible to the user. The naming container for a given control is the parent control above it in the hierarchy that implements the INamingContainer interface. A server control that implements this interface creates a unique namespace for the ID property values of its child server controls. You can use the NamingContainer property of a naming container's child control to get a reference to its parent container.

Creating a unique namespace for server controls is particularly important when you bind Web server controls to data, such as the Repeater and DataList server controls. When multiple entries in the data source create multiple instances of a server control that is a child of the repeating control, the naming container ensures that each instance of these child controls have UniqueID property values that do not conflict. The default naming container for a page is the instance of the Page class that is generated when that page is requested.

The ClientID property contains the value that is rendered as the element's id attribute in the HTML markup. Depending on the value that you assign to the ClientIDMode property, the value that is generated for the ClientID property might include the ID of the NamingContainer object. When you set ClientIDMode to Static, the ClientID value does not include the ID of the NamingContainer object. When you set ClientIDMode to either AutoID or Predictable, the ClientID value will include the ID from the NamingContainer object. For more information, see ASP.NET Web Server Control Identification.

Topic Location
How to: Access Members of a Web Server Control's Naming Container Building ASP .NET Web Applications
How to: Access Members of a Web Server Control's Naming Container Building ASP .NET Web Applications

The following example demonstrates using the NamingContainer property.

<%@ Import Namespace = "System.Data"  %>
<!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>
            Control NamingContainer Example
         </title>
<script language="VB" runat="server">
      ' Build the DataSource.
      Function CreateDataSource() As ICollection
         Dim myDataTable As New DataTable()
         Dim myDataRow As DataRow
         myDataTable.Columns.Add(New DataColumn("EmployeeName", GetType(String)))
         Dim i As Integer
         For i = 0 To 9
            myDataRow = myDataTable.NewRow()
            myDataRow(0) = "somename" + i.ToString()
            myDataTable.Rows.Add(myDataRow)
         Next i
         Dim myDataView As New DataView(myDataTable)
         Return myDataView
      End Function

      Sub Page_Load(sender As Object, e As EventArgs)
         If Not IsPostBack Then
            ' Bind 'DataView' to the DataSource.
            myDataList.DataSource = CreateDataSource()
            myDataList.DataBind()
         End If
         ' Attach EventHandler for SelectedIndexChanged event.
         AddHandler myDataList.SelectedIndexChanged, AddressOf selectedItemChanged
      End Sub

      ' Handler function for 'SelectedIndexChanged' event.
      Sub selectedItemChanged(sender As Object, e As EventArgs)
         Dim myCurrentItem As DataListItem = myDataList.SelectedItem
         Dim myNamingContainer As Control = myCurrentItem.Controls(0).NamingContainer
         ' Display the NamingContainer.
         myLabel1.Text = "The NamingContainer is : " + myNamingContainer.UniqueID
         ' Display the UniqueID.
         myLabel2.Text = "The UniqueID is : " + CType(myCurrentItem.Controls(0), Control).UniqueID
      End Sub
    </script>
   </head>
   <body>
      <form runat="server" id="Form1">
         <h3>
            Control NamingContainer Example
         </h3>
         <h4>
            Click an item to view it's Naming Container and UniqueID
         </h4>
         <asp:Label ID="myLabel1" Runat="server"></asp:Label>
         <br />
         <asp:Label ID="myLabel2" Runat="server"></asp:Label>
         <br />
         <asp:DataList id="myDataList" runat="server" BorderColor="black">
            <HeaderStyle BackColor="#aaaadd"></HeaderStyle>
            <SelectedItemStyle BackColor="lightgreen"></SelectedItemStyle>
            <HeaderTemplate>
               EmployeeName
            </HeaderTemplate>
            <ItemTemplate>
               <asp:LinkButton id="button1" Text='<%# DataBinder.Eval(Container.DataItem, "EmployeeName") %>' CommandName="select" runat="server" />
               &nbsp;&nbsp;&nbsp;&nbsp;
            </ItemTemplate>
         </asp:DataList>
      </form>
   </body>
</html>

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.