Python爬虫从入门到放弃（十九）之 Scrapy爬取所有知乎用户信息(下)

Posted 2020-09-29

在上一篇文章中主要写了关于爬虫过程的分析，下面是代码的实现，完整代码在：
https://github.com/pythonsite/spider

items中的代码主要是我们要爬取的字段的定义

class UserItem(scrapy.Item):
    id = Field()
    name = Field()
    account_status = Field()
    allow_message= Field()
    answer_count = Field()
    articles_count = Field()
    avatar_hue = Field()
    avatar_url = Field()
    avatar_url_template = Field()
    badge = Field()
    business = Field()
    employments = Field()
    columns_count = Field()
    commercial_question_count = Field()
    cover_url = Field()
    description = Field()
    educations = Field()
    favorite_count = Field()
    favorited_count = Field()
    follower_count = Field()
    following_columns_count = Field()
    following_favlists_count = Field()
    following_question_count = Field()
    following_topic_count = Field()
    gender = Field()
    headline = Field()
    hosted_live_count = Field()
    is_active = Field()
    is_bind_sina = Field()
    is_blocked = Field()
    is_advertiser = Field()
    is_blocking = Field()
    is_followed = Field()
    is_following = Field()
    is_force_renamed = Field()
    is_privacy_protected = Field()
    locations = Field()
    is_org = Field()
    type = Field()
    url = Field()
    url_token = Field()
    user_type = Field()
    logs_count = Field()
    marked_answers_count = Field()
    marked_answers_text = Field()
    message_thread_token = Field()
    mutual_followees_count = Field()
    participated_live_count = Field()
    pins_count = Field()
    question_count = Field()
    show_sina_weibo = Field()
    thank_from_count = Field()
    thank_to_count = Field()
    thanked_count = Field()
    type = Field()
    vote_from_count = Field()
    vote_to_count = Field()
    voteup_count = Field()

这些字段的是在用户详细信息里找到的，如下图所示，这里一共有58个字段，可以详细研究每个字段代表的意思：

关于spiders中爬虫文件zhihu.py中的主要代码

这段代码是非常重要的，主要的处理逻辑其实都是在这里

class ZhihuSpider(scrapy.Spider):
    name = "zhihu"
    allowed_domains = ["www.zhihu.com"]
    start_urls = [‘http://www.zhihu.com/‘]
    #这里定义一个start_user存储我们找的大V账号
    start_user = "excited-vczh"

    #这里把查询的参数单独存储为user_query,user_url存储的为查询用户信息的url地址
    user_url = "https://www.zhihu.com/api/v4/members/{user}?include={include}"
    user_query = "locations,employments,gender,educations,business,voteup_count,thanked_Count,follower_count,following_count,cover_url,following_topic_count,following_question_count,following_favlists_count,following_columns_count,avatar_hue,answer_count,articles_count,pins_count,question_count,columns_count,commercial_question_count,favorite_count,favorited_count,logs_count,marked_answers_count,marked_answers_text,message_thread_token,account_status,is_active,is_bind_phone,is_force_renamed,is_bind_sina,is_privacy_protected,sina_weibo_url,sina_weibo_name,show_sina_weibo,is_blocking,is_blocked,is_following,is_followed,mutual_followees_count,vote_to_count,vote_from_count,thank_to_count,thank_from_count,thanked_count,description,hosted_live_count,participated_live_count,allow_message,industry_category,org_name,org_homepage,badge[?(type=best_answerer)].topics"

    #follows_url存储的为关注列表的url地址,fllows_query存储的为查询参数。这里涉及到offset和limit是关于翻页的参数，0，20表示第一页
    follows_url = "https://www.zhihu.com/api/v4/members/{user}/followees?include={include}&offset={offset}&limit={limit}"
    follows_query = "data%5B*%5D.answer_count%2Carticles_count%2Cgender%2Cfollower_count%2Cis_followed%2Cis_following%2Cbadge%5B%3F(type%3Dbest_answerer)%5D.topics"

    #followers_url是获取粉丝列表信息的url地址，followers_query存储的为查询参数。
    followers_url = "https://www.zhihu.com/api/v4/members/{user}/followers?include={include}&offset={offset}&limit={limit}"
    followers_query = "data%5B*%5D.answer_count%2Carticles_count%2Cgender%2Cfollower_count%2Cis_followed%2Cis_following%2Cbadge%5B%3F(type%3Dbest_answerer)%5D.topics"


    def start_requests(self):
        ‘‘‘
        这里重写了start_requests方法，分别请求了用户查询的url和关注列表的查询以及粉丝列表信息查询
        :return:
        ‘‘‘
        yield Request(self.user_url.format(user=self.start_user,include=self.user_query),callback=self.parse_user)
        yield Request(self.follows_url.format(user=self.start_user,include=self.follows_query,offset=0,limit=20),callback=self.parse_follows)
        yield Request(self.followers_url.format(user=self.start_user,include=self.followers_query,offset=0,limit=20),callback=self.parse_followers)

    def parse_user(self, response):
        ‘‘‘
        因为返回的是json格式的数据，所以这里直接通过json.loads获取结果
        :param response:
        :return:
        ‘‘‘
        result = json.loads(response.text)
        item = UserItem()
        #这里循环判断获取的字段是否在自己定义的字段中，然后进行赋值
        for field in item.fields:
            if field in result.keys():
                item[field] = result.get(field)

        #这里在返回item的同时返回Request请求，继续递归拿关注用户信息的用户获取他们的关注列表
        yield item
        yield Request(self.follows_url.format(user = result.get("url_token"),include=self.follows_query,offset=0,limit=20),callback=self.parse_follows)
        yield Request(self.followers_url.format(user = result.get("url_token"),include=self.followers_query,offset=0,limit=20),callback=self.parse_followers)




    def parse_follows(self, response):
        ‘‘‘
        用户关注列表的解析，这里返回的也是json数据 这里有两个字段data和page，其中page是分页信息
        :param response:
        :return:
        ‘‘‘
        results = json.loads(response.text)

        if ‘data‘ in results.keys():
            for result in results.get(‘data‘):
                yield Request(self.user_url.format(user = result.get("url_token"),include=self.user_query),callback=self.parse_user)

        #这里判断page是否存在并且判断page里的参数is_end判断是否为False，如果为False表示不是最后一页，否则则是最后一页
        if ‘page‘ in results.keys() and results.get(‘is_end‘) == False:
            next_page = results.get(‘paging‘).get("next")
            #获取下一页的地址然后通过yield继续返回Request请求，继续请求自己再次获取下页中的信息
            yield Request(next_page,self.parse_follows)

    def parse_followers(self, response):
        ‘‘‘
        这里其实和关乎列表的处理方法是一样的
        用户粉丝列表的解析，这里返回的也是json数据 这里有两个字段data和page，其中page是分页信息
        :param response:
        :return:
        ‘‘‘
        results = json.loads(response.text)

        if ‘data‘ in results.keys():
            for result in results.get(‘data‘):
                yield Request(self.user_url.format(user = result.get("url_token"),include=self.user_query),callback=self.parse_user)

        #这里判断page是否存在并且判断page里的参数is_end判断是否为False，如果为False表示不是最后一页，否则则是最后一页
        if ‘page‘ in results.keys() and results.get(‘is_end‘) == False:
            next_page = results.get(‘paging‘).get("next")
            #获取下一页的地址然后通过yield继续返回Request请求，继续请求自己再次获取下页中的信息
            yield Request(next_page,self.parse_followers)

上述的代码的主要逻辑用下图分析表示：

 

关于上图的一个简单描述：
1. 当重写start_requests，一会有三个yield，分别的回调函数调用了parse_user,parse_follows,parse_followers，这是第一次会分别获取我们所选取的大V的信息以及关注列表信息和粉丝列表信息
2. 而parse分别会再次回调parse_follows和parse_followers信息，分别递归获取每个用户的关注列表信息和分析列表信息
3. parse_follows获取关注列表里的每个用户的信息回调了parse_user，并进行翻页获取回调了自己parse_follows
4. parse_followers获取粉丝列表里的每个用户的信息回调了parse_user，并进行翻页获取回调了自己parse_followers

通过上面的步骤实现所有用户信息的爬取，最后是关于数据的存储

关于数据存储到mongodb

这里主要是item中的数据存储到mongodb数据库中，这里主要的一个用法是就是插入的时候进行了一个去重检测

class MongoPipeline(object):

    def __init__(self, mongo_uri, mongo_db):
        self.mongo_uri = mongo_uri
        self.mongo_db = mongo_db

    @classmethod
    def from_crawler(cls, crawler):
        return cls(
            mongo_uri=crawler.settings.get(‘MONGO_URI‘),
            mongo_db=crawler.settings.get(‘MONGO_DATABASE‘, ‘items‘)
        )

    def open_spider(self, spider):
        self.client = pymongo.MongoClient(self.mongo_uri)
        self.db = self.client[self.mongo_db]

    def close_spider(self, spider):
        self.client.close()

    def process_item(self, item, spider):
        #这里通过mongodb进行了一个去重的操作，每次更新插入数据之前都会进行查询，判断要插入的url_token是否已经存在，如果不存在再进行数据插入，否则放弃数据
        self.db[‘user‘].update({‘url_token‘:item["url_token"]},{‘$set‘:item},True)
        return item