public async Task <IActionResult> PutBook(long id, Book book) { if (id != book.Id) { return(BadRequest()); } _context.Entry(book).State = EntityState.Modified; try { await _context.SaveChangesAsync(); } catch (DbUpdateConcurrencyException) { if (!BookExists(id)) { return(NotFound()); } else { throw; } } return(NoContent()); }