TemplateInstanceAttribute Class
Definition
Important
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Defines a metadata attribute that is used to specify the number of allowed instances of a template. This class cannot be inherited.
public ref class TemplateInstanceAttribute sealed : Attribute[System.AttributeUsage(System.AttributeTargets.Property)]
public sealed class TemplateInstanceAttribute : Attribute[<System.AttributeUsage(System.AttributeTargets.Property)>]
type TemplateInstanceAttribute = class
inherit AttributePublic NotInheritable Class TemplateInstanceAttribute
Inherits Attribute- Inheritance
- Attributes
Examples
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;
}
}
}
}
Imports System.Data
Imports System.ComponentModel
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls
Namespace Samples.AspNet.VB.Controls
Public Class MyLoginViewA
Inherits LoginView
Private _anonymoustemplate As ITemplate
<Browsable(False), DefaultValue(""), PersistenceMode(PersistenceMode.InnerProperty), TemplateContainer(GetType(LoginView)), TemplateInstance(TemplateInstance.Single)> _
Public Overrides Property AnonymousTemplate() As System.Web.UI.ITemplate
Get
Return _anonymoustemplate
End Get
Set(ByVal value As System.Web.UI.ITemplate)
_anonymoustemplate = value
End Set
End Property
End Class
End Namespace
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">
// <Snippet3>
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.");
}
}
// </Snippet3>
</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>
<%@ Page Language="VB" %>
<%@ Import Namespace="System.Reflection" %>
<%@ Register TagPrefix="AspNetSamples" Namespace="Samples.AspNet.VB.Controls" Assembly="Samples.AspNet.VB.Controls" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
' <Snippet3>
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)
' Get the class type for which to access metadata.
Dim clsType As Type = GetType(MyLoginViewA)
' Get the PropertyInfo object for FirstTemplate.
Dim pInfo As PropertyInfo = clsType.GetProperty("AnonymousTemplate")
' See if the TemplateInstanceAttribute is defined for this property.
Dim isDef As Boolean = Attribute.IsDefined(pInfo, GetType(TemplateContainerAttribute))
' Display the result if the attribute exists.
If isDef Then
Dim tia As TemplateInstanceAttribute = CType(Attribute.GetCustomAttribute(pInfo, GetType(TemplateInstanceAttribute)), TemplateInstanceAttribute)
Response.Write("The <AnonymousTemplate> has the TemplateInstanceAttribute = " & tia.Instances.ToString() & ".<br />")
If (tia.IsDefaultAttribute()) Then
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.")
End If
End If
End Sub
' </Snippet3>
</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>
Remarks
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 Attributes.
Constructors
| TemplateInstanceAttribute(TemplateInstance) |
Initializes a new instance of the TemplateInstanceAttribute class with the specified TemplateInstance enumeration value. |
Fields
| Default |
Defines the default value for the TemplateInstanceAttribute class. This field is read-only. |
| Multiple |
Creates an instance of the TemplateInstanceAttribute class as one representing a template that will be instantiated multiple times. This field is read-only. |
| Single |
Creates an instance of the TemplateInstanceAttribute class as one representing a template that will be instantiated a single time. This field is read-only. |
Properties
| Instances |
Gets the TemplateInstance enumeration value that the current template instance represents. |
| TypeId |
When implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute) |
Methods
| Equals(Object) |
Indicates whether the specified object is a TemplateInstanceAttribute object and is identical to the this TemplateInstanceAttribute object. |
| GetHashCode() |
Gets a hash code for this TemplateInstanceAttribute object. |
| GetType() |
Gets the Type of the current instance. (Inherited from Object) |
| IsDefaultAttribute() |
Returns a value indicating if the current TemplateInstanceAttribute object is the same as the default TemplateInstanceAttribute object. |
| Match(Object) |
When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute) |
| MemberwiseClone() |
Creates a shallow copy of the current Object. (Inherited from Object) |
| ToString() |
Returns a string that represents the current object. (Inherited from Object) |
Explicit Interface Implementations
| _Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr) |
Maps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute) |
| _Attribute.GetTypeInfo(UInt32, UInt32, IntPtr) |
Retrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute) |
| _Attribute.GetTypeInfoCount(UInt32) |
Retrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute) |
| _Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr) |
Provides access to properties and methods exposed by an object. (Inherited from Attribute) |
