// [TempData]
        // public string errorMessage { get; set; }

        public VoteController(ApplicationDBContext context,
                              IAttendeeProvider attendeeProvider,
                              ITeamProvider teamProvider) : base(context)
        {
            _attendeeProvider = attendeeProvider;
            _teamProvider     = teamProvider;
        }
 public RegistrationController(ApplicationDBContext context,
                               IAttendeeProvider attendeeProvider) : base(context)
 {
     _attendeeProvider = attendeeProvider;
 }
 public TeamProvider(ApplicationDBContext context,
                     IAttendeeProvider attendeeProvider)
 {
     _context          = context;
     _attendeeProvider = attendeeProvider;
 }