public PhoneBookUser CreateUser(PhoneBookUser user)
        {
            var result = _context.Add(user);

            _context.SaveChanges();

            if (result != null)
            {
                return(user);
            }

            return(null);
        }
        public bool UpdateUser(int id, PhoneBookUser user)
        {
            var existingPhoneBookUser = _context.PhoneBookUsers.Where(x => x.Id == id).FirstOrDefault();

            if (existingPhoneBookUser != null)
            {
                existingPhoneBookUser = user;

                _context.PhoneBookUsers.Update(existingPhoneBookUser);
                _context.SaveChanges();

                return(true);
            }

            return(false);
        }