def parse_answer(self, response):
    answer_item_loader = ZhihuItemLoader(item=ZhihuAnswerItem(), response=response)
    answer_dict = json.loads(response.text)

    is_end = answer_dict['paging']['is_end']
    next_answer_url = answer_dict['paging']['next']

    for answer in answer_dict['data']:
        create_time = answer['created_time']
        update_time = answer['updated_time']
        answer_id = answer['id']
        praise_nums = answer['voteup_count']
        answer_url = answer['url']
        author_id = answer['author']['id'] if 'id' in answer['author'] else ''
        question_id = answer['question']['id']
        question_create_time = answer['question']['created']
        question_update_time = answer['question']['updated_time']
        content = answer['content'] if 'content' in answer['content'] else answer['excerpt']
        comment_nums = answer['comment_count']
        crawl_time = datetime.now()

        answer_item_loader.add_value('answer_id', answer_id)
        answer_item_loader.add_value('question_id', question_id)
        answer_item_loader.add_value('answer_url', answer_url)
        answer_item_loader.add_value('author_id', author_id)
        answer_item_loader.add_value('content', content)
        answer_item_loader.add_value('praise_nums', praise_nums)
        answer_item_loader.add_value('comment_nums', comment_nums)
        answer_item_loader.add_value('create_time', create_time)
        answer_item_loader.add_value('update_time', update_time)
        answer_item_loader.add_value('crawl_time', crawl_time)

        answer_item = answer_item_loader.load_item()
        yield answer_item

    if is_end == False:
        yield scrapy.Request(next_answer_url, callback=self.parse_answer)