Injecting an IPrincipal with Unity Property Injection at runtime

Question

Using Unity in an ASP.Net MVC 2 app I have various dependencies on Controllers instantiated correctly. However, I want to ensure that the current IPrincipal for the user is going to be passed via injection to lower level Services, Repository etc.

Therefore in a lower level service I have something like:

[Dependency] IPrincipal CurrentUser {get; set;}

If I use Property Dependency Injection I do not get what I want because the Controller is instantiated BEFORE a User principal is available and in any case Unity does not know to get the current user credentials.

So what I want is to be able to inject the current user's IPrincipal (or probably RolePrincipal) into one of the dependencies for the Controller.

How can I do this?

Answer 1

Why not take the direct route, and just assign it.

Thread.CurrentPrincipal = user;

Dependency injection is good, but don't let it get in the way of the best dependency injector, the programmer.

Answer 2

Why inject it? The current principal is already present as User. That is what we use, and it works fine so far. The user shouldn't change within a single request, should it?

protected void Application_AuthenticateRequest()
{
    var ticket = GetAuthenticationTicket();
    // Perform actual authentication, etc.
    MyUser user = BigAuthStuff();
    Context.User = user;
    Thread.CurrentPrincipal = user;
}

public class MyBaseController : Controller
{
    protected MyUser AuthenticatedUser
    {
        get { return User as MyUser; }
    }
}