public IActionResult AddAuthorToBook(long idAuthor, [FromBody] Author item)
        {
            if (item == null || item.authorid != idAuthor)
            {
                return(BadRequest());
            }
            var author = authorRepository.FindByID(idAuthor);

            if (author == null)
            {
                return(NotFound("Could not find book with id : " + idAuthor + ". Please try again with valid id."));
            }

            author.bookauthor = item.bookauthor;

            Author updatedBook = authorRepository.AddAuthorToBook(author);

            Console.WriteLine(" updatedBook = " + (updatedBook == null));

            if (updatedBook.authorid == -1)
            {
                return(NotFound("Invalid author id : " + updatedBook.fname + ". Please try again"));
            }

            return(CreatedAtRoute("AddBook", new { idBook = idAuthor }, updatedBook));
        }