How can I make accessing my custom IPrincipal easier in ASP.NET MVC?

Question

I\'ve written a custom principal object which contains a few additional fields (email and userid in addition to the username).

In order to access these properties I have

Answer 1

I whipped something together quickly. One possible way of easily introducing a custom IPrincipal in ASP.NET MVC is the following:

1) Create your own descendant of the IPrincipal interface.

public interface IMyPrincipal : IPrincipal
{
    Guid UserId { get; }
    string EmailAddress { get; }
}

2) Let's assume you are using the ASP.NET Membership provider to authenticate your users. Let's quickly build an IMyPrincipal implementation which utilizes the membership API.

public class MyPrincipal : IMyPrincipal
{
    private MembershipUser _user;

    public MyPrincipal()
    {
        this._user = Membership.GetUser();
        var userName = this._user != null ? this._user.UserName : String.Empty;
        this.Identity = new GenericIdentity(userName);
    }

    public Guid UserId
    {
        get 
        { 
            return this._user != null ? (Guid) this._user.ProviderUserKey : 
                                        default(Guid);
        }
    }

    public string EmailAddress
    {
        get 
        { 
            return this._user != null ? this._user.Email : null;
        }
    }

    public IIdentity Identity { get; private set; }
    public bool IsInRole(string role) { return false; }
}

3) Create your own base class type for your controllers. Hide the inherited User member and introduce your own IPrincipal descendant.

public class BaseController : Controller
{
    protected virtual new MyPrincipal User
    {
        get { return HttpContext.User as MyPrincipal; }
    }
}   

4) Have all your controllers descend from this new BaseController type.

public class HomeController : BaseController
{
  //...
}

5) Create your own controller factory to make sure your principal is introduced on the HttpContext / Thread.

public class MyControllerFactory : DefaultControllerFactory
{
    protected override IController GetControllerInstance
        (RequestContext requestContext, Type controllerType)
    {
        try
        {
            var controller = base.GetControllerInstance(requestContext, controllerType);
            requestContext.HttpContext.User = Thread.CurrentPrincipal = new 
                                                    MyPrincipal();
            return controller;
        }
        catch (Exception)
        {
            return base.GetControllerInstance(requestContext, controllerType);
        }
    }
}

6) Register the controller factory in the Global.asax's Application_Start() event handler.

var controllerFactory = new MyControllerFactory();
ControllerBuilder.Current.SetControllerFactory(controllerFactory);

Voila, now you can use the new User (IMyPrincipal) anywhere in your controllers.

For example:

public ActionResult Index()
{
    ViewBag.Message = "Welcome to ASP.NET MVC!";

    ViewBag.UserId = User.UserId;
    ViewBag.UserName = User.EmailAddress;

    return View();
}