// GET: api/Authors/5
        public IHttpActionResult GetAuthorById(int id)
        {
            var author = db.Authors.Select(a => new
            {
                Id = a.Id,
                FirstName = a.FirstName,
                LastName = a.LastName,
                BookTitles = a.Books.Select(b => b.Title)
            })
            .FirstOrDefault(a => a.Id == id);
        
            if (author == null)
            {
                return NotFound();
            }

            var authorView = new AuthorViewModel.AuthorBookViewModel()
            {
                FirstName = author.FirstName,
                LastName = author.LastName,
                BookTitles = author.BookTitles
            };

            return this.Ok(authorView);
        }
        public IHttpActionResult GetBooksForAuthorById(int id)
        {
            var author = db.Authors.FirstOrDefault(a => a.Id == id);
            
            if (author == null)
            {
                return this.NotFound();
            }

            var authorView = new AuthorViewModel.AuthorBookViewModel()
            {
                BookTitles = author.Books.Select(b => b.Title)
            };

            return this.Ok(authorView);
        }