I'm new to MVC and have a question. The Visual Studio template creates a table dbo.AspNetUsers that has a column called Id. From my controller I want to get that value for the user who is signed in 
    public ActionResult Index ()
    {
        if (!Request.IsAuthenticated) // if not logged in 
        {
            Response.StatusCode = 404;
            return null;
        }
        else
        {
             string thisUserId = ???
             // do something with thisUserId
        }
I've looked through the source files but can't figure out how I get this.
 
     
    