functional python: item vs attribute

import json
from operator import attrgetter, itemgetter

class Book:
    def __init__(self, **kwargs):
        for k, v in kwargs.items():
            setattr(self, k, v)

    def __str__(self):
        return self.title

    def __repr__(self):
        return str(self)


def get_books(filename, raw=False):
    try:
        data = json.load(open(filename))
    except FileNotFoundError:
        return []
    else:
        if raw:
            return data['books']
        return [Book(**book) for book in data['books']]

BOOKS = get_books('books.json')
RAW_BOOKS = get_books('books.json', raw=True)

# pub_sort = sorted(RAW_BOOKS, key=itemgetter('publish_date'))
# print(pub_sort[0]['publish_date'], pub_sort[-1]['publish_date'])
pages_sort = sorted(BOOKS, key=attrgetter('number_of_pages'))
print(pages_sort[0].number_of_pages, pages_sort[-1].number_of_pages)

#important_list = [5, 3, 1, 2, 4]
#important_list.sort()  # Bad idea, sorts list in place
# sorted(important_list)  # Sorts a copy of the list