private void updateBookFields(Book book, BookDto bookDto) {
book.setAuthor(bookDto.getAuthor());
book.setDescription(bookDto.getDescription());
book.setBookLanguage(bookDto.getLanguage());
book.setPages(bookDto.getPages());
book.setTitle(bookDto.getTitle());
book.setYear(bookDto.getYear());
String categoryId = null;
if (!bookDto.getCategory().equals("default")) categoryId = bookDto.getCategory();
book.setCategory(categoryId);
}
