AuthorizeAttribute Class

Článek
02/21/2011

Represents an attribute that is used to restrict access by callers to an action method.

Inheritance Hierarchy

System.Object
  System.Attribute
    System.Web.Mvc.FilterAttribute
      System.Web.Mvc.AuthorizeAttribute

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

Syntax

'Declaration
<AttributeUsageAttribute(AttributeTargets.Class Or AttributeTargets.Method, Inherited := True,  _
    AllowMultiple := True)> _
Public Class AuthorizeAttribute _
    Inherits FilterAttribute _
    Implements IAuthorizationFilter

[AttributeUsageAttribute(AttributeTargets.Class|AttributeTargets.Method, Inherited = true, 
    AllowMultiple = true)]
public class AuthorizeAttribute : FilterAttribute, 
    IAuthorizationFilter

[AttributeUsageAttribute(AttributeTargets::Class|AttributeTargets::Method, Inherited = true, 
    AllowMultiple = true)]
public ref class AuthorizeAttribute : public FilterAttribute, 
    IAuthorizationFilter

The AuthorizeAttribute type exposes the following members.

Constructors

	Name	Description
	AuthorizeAttribute	Initializes a new instance of the AuthorizeAttribute class.

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Properties

	Name	Description
	Order	Gets or sets the order in which the action filters are executed. (Inherited from FilterAttribute.)
	Roles	Gets or sets the user roles.
	TypeId	Gets the unique identifier for this attribute. (Overrides Attribute.TypeId.)
	Users	Gets or sets the authorized users.

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Methods

	Name	Description
	AuthorizeCore	Determines whether access to the core framework is authorized.
	Equals	Infrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
	GetHashCode	Returns the hash code for this instance. (Inherited from Attribute.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	HandleUnauthorizedRequest	Processes HTTP requests that fail authorization.
	IsDefaultAttribute	When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute.)
	Match	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.)
	OnAuthorization	Called when a process requests authorization.
	OnCacheAuthorization	Called when the caching module requests authorization.
	ToString	Returns a string that represents the current object. (Inherited from Object.)

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Explicit Interface Implementations

	Name	Description
	_Attribute.GetIDsOfNames	Maps a set of names to a corresponding set of dispatch identifiers. (Inherited from Attribute.)
	_Attribute.GetTypeInfo	Retrieves the type information for an object, which can be used to get the type information for an interface. (Inherited from Attribute.)
	_Attribute.GetTypeInfoCount	Retrieves the number of type information interfaces that an object provides (either 0 or 1). (Inherited from Attribute.)
	_Attribute.Invoke	Provides access to properties and methods exposed by an object. (Inherited from Attribute.)

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Remarks

Many Web applications require users to log in before the users are granted access to restricted content. In some applications, even users who are logged in might have restrictions on what content they can view or what fields they can edit.

To restrict access to an ASP.NET MVC view, you restrict access to the action method that renders the view. To accomplish this, the MVC framework provides the AuthorizeAttribute class.

For more information about using attributes, see Extending Metadata Using Attributes.

This topic contains the following sections:

Using AuthorizeAttribute
Deriving from AuthorizeAttribute

Using AuthorizeAttribute

When you mark an action method with AuthorizeAttribute, access to that action method is restricted to users who are both authenticated and authorized. If you mark a controller with the attribute, all action methods in the controller are restricted.

The Authorize attribute lets you indicate that authorization is restricted to predefined roles or to individual users. This gives you a high degree of control over who is authorized to view any page on the site.

If an unauthorized user tries to access a method that is marked with the Authorize attribute, the MVC framework returns a 401 HTTP status code. If the site is configured to use ASP.NET forms authentication, the 401 status code causes the browser to redirect the user to the login page.

Deriving from AuthorizeAttribute

If you derive from the AuthorizeAttribute class, the derived type must be thread safe. Therefore, do not store state in an instance of the type itself (for example, in an instance field) unless that state is meant to apply to all requests. Instead, store state per request in the Items property, which is accessible through the context objects passed to AuthorizeAttribute.

Examples

The following example shows several ways to use AuthorizeAttribute. The HomeController class has three action methods that are marked with the Authorize attribute, and two that are not marked. On the AuthenticatedUsers method, the attribute limits access to users who are logged in. On the AdministratorsOnly method, the attribute limits access to users who have been assigned to either the Admin role or the Super User role. On the SpecificUserOnly method, the attribute limits access to the users whose names are Betty or Johnny. The Index and About methods can be accessed by anyone, even anonymous users.

<HandleError()> _
Public Class HomeController
    Inherits System.Web.Mvc.Controller

    Function Index() As ActionResult
        ViewData("Message") = "Welcome to ASP.NET MVC!"

        Return View()
    End Function

    Function About() As ActionResult
        Return View()
    End Function

    <Authorize()> _
    Function AuthenticatedUsers()
        Return View()
    End Function

    <Authorize(Roles:="Admin, Super User")> _
    Function AdministratorsOnly()
        Return View()
    End Function

    <Authorize(Users:="Betty, Johnny")> _
    Function SpecificUserOnly()
        Return View()
    End Function
End Class

[HandleError]
 public class HomeController : Controller
 {
     public ActionResult Index()
     {
         ViewData["Message"] = "Welcome to ASP.NET MVC!";

         return View();
     }

     public ActionResult About()
     {
         return View();
     }

     [Authorize]
     public ActionResult AuthenticatedUsers()
     {
         return View();
     }

     [Authorize(Roles = "Admin, Super User")]
     public ActionResult AdministratorsOnly()
     {
         return View();
     }

     [Authorize(Users = "Betty, Johnny")]
     public ActionResult SpecificUserOnly()
     {
         return View();
     }
 }

Thread Safety

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

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