public IActionResult ModifyAuthor(int id, AuthorCreationData request)
        {
            if (!ModelState.IsValid)
            {
                return(BadRequest(ModelState));
            }

            Author existing = _context.Authors
                              .SingleOrDefault(c => c.Id == id);

            if (existing != null)
            {
                existing.Name      = request.Name;
                existing.Surname   = request.Surname;
                existing.BirthDate = request.Birth;
                existing.DeathDate = request.Death;
                foreach (var property in _context.Entry(existing).Properties.Where(c => c.CurrentValue == null && c.IsModified))
                {
                    property.IsModified = false;
                }
                _context.SaveChanges();
                return(Ok());
            }

            return(BadRequest());
        }
        public IActionResult CreateAuthor(AuthorCreationData request)
        {
            if (!ModelState.IsValid)
            {
                return(BadRequest(ModelState));
            }

            _context
            .Authors
            .Add(new Author()
            {
                Name      = request.Name,
                Surname   = request.Surname,
                BirthDate = request.Birth,
                DeathDate = request.Death
            });

            _context.SaveChanges();
            return(Ok(new
            {
                message = "Naujas autorius sukurtas."
            }));
        }