AuthorizationAttribute Class

Artigo
01/27/2012

[WCF RIA Services Version 1 Service Pack 2 is compatible with either .NET framework 4 or .NET Framework 4.5, and with either Silverlight 4 or Silverlight 5.]

Serves as base class for classes that are used to control authorization through custom metadata.

Inheritance Hierarchy

System.Object
  System.Attribute
    System.ComponentModel.DataAnnotations.AuthorizationAttribute
      System.ServiceModel.DomainServices.Server.RequiresAuthenticationAttribute
      System.ServiceModel.DomainServices.Server.RequiresRoleAttribute

Namespace: System.ComponentModel.DataAnnotations
Assembly: System.ServiceModel.DomainServices.Server (in System.ServiceModel.DomainServices.Server.dll)

Syntax

'Declaration
Public MustInherit Class AuthorizationAttribute _
    Inherits Attribute

'Usage
Dim instance As AuthorizationAttribute

public abstract class AuthorizationAttribute : Attribute

public ref class AuthorizationAttribute abstract : public Attribute

[<AbstractClassAttribute>]
type AuthorizationAttribute =  
    class
        inherit Attribute
    end

public abstract class AuthorizationAttribute extends Attribute

The AuthorizationAttribute type exposes the following members.

Constructors

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

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Properties

	Name	Description
	ErrorMessage	Gets or sets the literal error message or resource key intended to be returned in an ErrorMessage.
	ResourceType	Gets or sets the Type to use as the resource manager for ErrorMessage.
	TypeId	(Inherited from Attribute.)

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Methods

	Name	Description
	Authorize	Determines whether the given principal object is authorized to perform a specific operation described by the given AuthorizationContext.
	Equals	(Inherited from Attribute.)
	Finalize	(Inherited from Object.)
	FormatErrorMessage	Gets the formatted error message for the current AuthorizationAttribute to present to the user.
	GetHashCode	(Inherited from Attribute.)
	GetType	(Inherited from Object.)
	IsAuthorized	Implementation specific method to determine whether the given IPrincipal object is authorized to perform a specific operation described by the given AuthorizationContext object.
	IsDefaultAttribute	(Inherited from Attribute.)
	Match	(Inherited from Attribute.)
	MemberwiseClone	(Inherited from Object.)
	ToString	(Inherited from Object.)

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Explicit Interface Implementations

	Name	Description
	_Attribute.GetIDsOfNames	(Inherited from Attribute.)
	_Attribute.GetTypeInfo	(Inherited from Attribute.)
	_Attribute.GetTypeInfoCount	(Inherited from Attribute.)
	_Attribute.Invoke	(Inherited from Attribute.)

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Remarks

You create a class that derives from the AuthorizationAttribute class to implement a customized authorization policy. When you create a derived class, you must implement the authorization logic in the IsAuthorized method. The IsAuthorized method includes parameters for an IPrincipal object and an AuthorizationContext object. You can use these parameters to determine if a user is authorized. In the derived class, you can add properties that are specified in the attribute declaration and used in the authorization logic. You apply the attribute to operations that need the customized authorization policy.

Examples

The following example shows an implementation of the AuthorizationAttribute class.

Public Class CheckAttendeeNameAttribute
    Inherits System.Web.DomainServices.AuthorizationAttribute


    Public Overrides Function Authorize(ByVal principal As System.Security.Principal.IPrincipal) As Boolean
        If (principal.IsInRole("Attendee") And principal.Identity.Name.StartsWith("A")) Then
            Return True
        Else
            Return False
        End If
    End Function
End Class

Public Class RestrictAccessToAssignedManagers
    Inherits AuthorizationAttribute

    Protected Overrides Function IsAuthorized(ByVal principal As System.Security.Principal.IPrincipal, ByVal authorizationContext As System.ComponentModel.DataAnnotations.AuthorizationContext) As System.ComponentModel.DataAnnotations.AuthorizationResult
        Dim eph As EmployeePayHistory
        Dim selectedEmployee As Employee
        Dim authenticatedUser As Employee

        eph = CType(authorizationContext.Instance, EmployeePayHistory)

        Using context As New AdventureWorksEntities()
            selectedEmployee = context.Employees.SingleOrDefault(Function(e) e.EmployeeID = eph.EmployeeID)
            authenticatedUser = context.Employees.SingleOrDefault(Function(e) e.LoginID = principal.Identity.Name)
        End Using

        If (selectedEmployee.ManagerID = authenticatedUser.EmployeeID) Then
            Return AuthorizationResult.Allowed
        Else
            Return New AuthorizationResult("Only the authenticated manager for the employee can add a new record.")
        End If
    End Function
End Class

public class CheckAttendeeNameAttribute : System.Web.DomainServices.AuthorizationAttribute
{

    public override bool Authorize(System.Security.Principal.IPrincipal principal)
    {
        if (principal.IsInRole("Attendee") && principal.Identity.Name.StartsWith("A"))
        {
            return true;
        }
        else
        {
            return false;
        }
    }
}

public class RestrictAccessToAssignedManagers : AuthorizationAttribute
{
    protected override AuthorizationResult IsAuthorized(System.Security.Principal.IPrincipal principal, AuthorizationContext authorizationContext)
    {
        EmployeePayHistory eph = (EmployeePayHistory)authorizationContext.Instance;
        Employee selectedEmployee;
        Employee authenticatedUser;

        using (AdventureWorksEntities context = new AdventureWorksEntities())
        {
            selectedEmployee = context.Employees.SingleOrDefault(e => e.EmployeeID == eph.EmployeeID);
            authenticatedUser = context.Employees.SingleOrDefault(e => e.LoginID == principal.Identity.Name);
        }

        if (selectedEmployee.ManagerID == authenticatedUser.EmployeeID)
        {
            return AuthorizationResult.Allowed;
        }
        else
        {
            return new AuthorizationResult("Only the authenticated manager for the employee can add a new record.");
        }
    }
}

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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