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TemplateInstanceAttribute Class

Defines a metadata attribute that is used to specify the number of allowed instances of a template. This class cannot be inherited.

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

[AttributeUsageAttribute(AttributeTargets.Property)]
[AspNetHostingPermissionAttribute(SecurityAction.LinkDemand, Level = AspNetHostingPermissionLevel.Minimal)]
public sealed class TemplateInstanceAttribute : Attribute

The TemplateInstanceAttribute class allows you to mark a template property as one that allows single or multiple instantiations. A template that only allows a single instantiation can have the controls that are contained inside of it referenced. The ZoneTemplate property is an example of a property that can be instantiated only one time.

This TemplateInstanceAttribute class is optional. If a template property is not extended with a TemplateInstanceAttribute class, the default value, the Multiple field, is used. For more information about using attributes, see Extending Metadata Using Attributes.

The following code example demonstrates how to use the TemplateInstance enumeration and the TemplateInstanceAttribute class. A custom LoginView control named MyLoginViewA overrides the AnonymousTemplate property and uses the TemplateInstanceAttribute class to specify that only one instance of the AnonymousTemplate property is created.

using System;
using System.Data;
using System.ComponentModel;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace Samples.AspNet.CS.Controls
{
	public class MyLoginViewA : LoginView
	{
		private ITemplate _anonymoustemplate;

		[Browsable(false),
		DefaultValue(null),
		PersistenceMode(PersistenceMode.InnerProperty),
		TemplateContainer(typeof(LoginView)),
		TemplateInstance(TemplateInstance.Single)
		]
		public override ITemplate AnonymousTemplate
		{
			get
			{
				return _anonymoustemplate;
			}
			set
			{
				_anonymoustemplate = value;
			}
		}
	}
}

The following code example is an ASPX file that uses the MyLoginViewA control and demonstrates how to access properties of the TemplateInstanceAttribute class.

<%@ Page Language="C#" %>
<%@ Import Namespace="System.Reflection" %>
<%@ Register TagPrefix="AspNetSamples" Namespace="Samples.AspNet.CS.Controls" Assembly="Samples.AspNet.CS.Controls" %>
<!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)
  {

    // Get the class type for which to access metadata.
    Type clsType = typeof(MyLoginViewA);
    // Get the PropertyInfo object for FirstTemplate.
    PropertyInfo pInfo = clsType.GetProperty("AnonymousTemplate");
    // See if the TemplateInstanceAttribute is defined for this property. 
    bool isDef = Attribute.IsDefined(pInfo, typeof(TemplateInstanceAttribute));

    // Display the result if the attribute exists. 
    if (isDef)
    {
      TemplateInstanceAttribute tia =
        (TemplateInstanceAttribute)Attribute.GetCustomAttribute(pInfo, typeof(TemplateInstanceAttribute));
      Response.Write("The <AnonymousTemplate> has the TemplateInstanceAttribute = " + tia.Instances.ToString() + ".<br />");
      if (tia.IsDefaultAttribute())
        Response.Write("The TemplateInstanceAttribute used is the same as the default instance.");
      else
        Response.Write("The TemplateInstanceAttribute used is not the same as the default instance.");
    }

  }

</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>TemplateInstance Example</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
      <AspNetSamples:MyLoginViewA id="MyLoginViewA1" runat="server">
        <AnonymousTemplate>
          <asp:Label ID="LoginViewLabel1" runat="server" Text="LoginView Anonymous Template Text"/>
        </AnonymousTemplate>
      </AspNetSamples:MyLoginViewA>
    </div>
    </form>
</body>
</html>

System.Object
  System.Attribute
    System.Web.UI.TemplateInstanceAttribute

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

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

.NET Framework

Supported in: 3.5, 3.0, 2.0

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