public static void UpdateAttendance(EventGuest updatedGuest)
        {
            if (updatedGuest == null)
            {
                throw new ArgumentNullException(nameof(updatedGuest));
            }

            using (var db = new EventManagerDBContext())
            {
                var query = from guest in db.EventGuests
                            where guest.MeetingGuestID == updatedGuest.ID
                            select guest;
                var returnedGuest = query.First();

                if (returnedGuest == null)
                {
                    throw new IndexOutOfRangeException($"Event index {updatedGuest.ID} not found");
                }

                returnedGuest.GuestStatus = updatedGuest.GuestStatus;

                db.EventGuests.Update(returnedGuest);
                db.SaveChanges();
                //    SaveDatabase();
            }
        }
        public static EventGuest AddGuestToEvent(int eventId, ContactItemModel newGuest)
        {
            if (eventId < 0)
            {
                throw new ArgumentException($"{nameof(eventId)}: {eventId}");
            }
            else
            {
                using (var db = new EventManagerDBContext())
                {
                    // Look for event guest if it exists
                    var eventQuery = from eventGuest in db.EventGuests
                                     where eventGuest.ContactID == newGuest.ID &&
                                     eventGuest.MeetingID == eventId
                                     select eventGuest;
                    var result = eventQuery.FirstOrDefault();
                    if (result == null)
                    {
                        var meetingGuest = new MeetingGuest
                        {
                            ContactID   = newGuest.ID,
                            MeetingID   = eventId,
                            GuestStatus = GustArrivalStatus.Unknown
                        };

                        db.EventGuests.Add(meetingGuest);
                        db.SaveChanges();
                        var guest = new EventGuest
                        {
                            ContactID   = newGuest.ID,
                            Guest       = newGuest,
                            GuestStatus = GustArrivalStatus.Unknown,
                            ID          = meetingGuest.MeetingGuestID
                        };

                        return(guest);
                    }
                    else
                    {
                        return(new EventGuest
                        {
                            ContactID = result.ContactID,
                            Guest = newGuest,
                            ID = result.ContactID,
                            GuestStatus = result.GuestStatus
                        });
                    }
                }
            }
        }