$def with(book, preload=False) $ title = book.title $ author_names = None $if any(book.get_authors()): $ author_names = ", ".join(a.get("name", "Name missing") for a in book.get_authors()) $if not author_names: $ author_names = book.get('by_statement','') $ cover_url = book.get_cover_url("M") $ cover_lg = book.get_cover_url("L") $ src = cover_url or '/images/icons/avatar_book.png' $ srcset = '%s 2x' % (cover_lg or '/images/icons/avatar_book-lg.png') $if preload: $add_metatag(tag="link", **{'rel': 'preload', 'as': 'image', 'href': src, 'imagesrcset': srcset})