爬取知乎话题评论数据

为了爬取知乎话题评论数据，可以使用以下步骤：

1. 使用Scrapy框架创建一个爬虫项目。
2. 在爬虫项目中定义一个Spider，用于爬取知乎话题下的所有问题。
3. 在Spider中定义一个回调函数，用于解析每个问题页面并提取评论数据。
4. 使用XPath或BeautifulSoup等工具从页面中提取评论数据。
5. 将提取的评论数据存储到MongoDB数据库中。

以下是一个简单的示例代码，用于爬取知乎话题评论数据：

import scrapy
import json
from scrapy import Request
from scrapy.spiders import Spider

class ZhihuSpider(Spider):
    name = 'zhihu'
    allowed_domains = ['www.zhihu.com']
    start_urls = ['https://www.zhihu.com/topic/19552832/hot']

    def parse(self, response):
        # 解析话题页面，获取所有问题的链接
        question_links = response.xpath('//a[@class="question_link"]/@href')
        for link in question_links:
            yield Request(link.extract(), callback=self.parse_question)

    def parse_question(self, response):
        # 解析问题页面，获取所有评论
        question_id = response.url.split('/')[-1]
        api_url = f'https://www.zhihu.com/api/v4/questions/{question_id}/answers?include=data%5B%2A%5D.is_normal%2Cadmin_closed_comment%2Creward_info%2Cis_collapsed%2Cannotation_action%2Cannotation_detail%2Ccollapse_reason%2Cis_sticky%2Ccollapsed_by%2Csuggest_edit%2Ccomment_count%2Ccan_comment%2Ccontent%2Ceditable_content%2Cvoteup_count%2Creshipment_settings%2Ccomment_permission%2Ccreated_time%2Cupdated_time%2Creview_info%2Cquestion%2Cexcerpt%2Cis_labeled%2Clabel_info%2Crelationship.is_authorized%2Cis_author%2Cvoting%2Cis_thanked%2Cis_nothelp%2Cis_recognized%2Cpaid_info%2Cpaid_info_content%3Bdata%5B%2A%5D.mark_infos%5B%2A%5D.url%3Bdata%5B%2A%5D.author.follower_count%2Cbadge%5B%3F(type%3Dbest_answerer)%5D.topics&limit=20&offset=0&platform=desktop&sort_by=default'
        yield Request(api_url, callback=self.parse_comments)

    def parse_comments(self, response):
        # 解析评论API，获取所有评论
        comments = json.loads(response.body)['data']
        for comment in comments:
            yield {
                'author': comment['author']['name'],                'content': comment['content'],
                'voteup_count': comment['voteup_count']
            }