scrapy的pipeline是一个非常重要的模块，主要作用是将return的items写入到数据库、文件等持久化模块，下面我们就简单的了解一下pipelines的用法。
案例一：
items池
class ZhihuuserItem(scrapy.Item): # define the fields for your item here like: # name = scrapy.Field() id = scrapy.Field() name = scrapy.Field() avatar_url = scrapy.Field() headline = scrapy.Field() description = scrapy.Field() url = scrapy.Field() url_token = scrapy.Field() gender = scrapy.Field() cover_url = scrapy.Field() type = scrapy.Field() badge = scrapy.Field() answer_count = scrapy.Field() articles_count = scrapy.Field() commercial_question = scrapy.Field() favorite_count = scrapy.Field() favorited_count = scrapy.Field() follower_count = scrapy.Field() following_columns_count = scrapy.Field() following_count = scrapy.Field() pins_count = scrapy.Field() question_count = scrapy.Field() thank_from_count = scrapy.Field() thank_to_count = scrapy.Field() thanked_count = scrapy.Field() vote_from_count = scrapy.Field() vote_to_count = scrapy.Field() voteup_count = scrapy.Field() following_favlists_count = scrapy.Field() following_question_count = scrapy.Field() following_topic_count = scrapy.Field() marked_answers_count = scrapy.Field() mutual_followees_count = scrapy.Field() participated_live_count = scrapy.Field() locations = scrapy.Field() educations = scrapy.Field() employments = scrapy.Field()
写入MongoDB数据库的基本配置
#配置MongoDB数据库的连接信息MONGO_URL = '172.16.5.239'MONGO_PORT = 27017MONGO_DB = 'zhihuuser'#参数等于False，就等于告诉你这个网站你想取什么就取什么，不会读取每个网站的根目录下的禁止爬取列表(例如：www.baidu.com/robots.txt）ROBOTSTXT_OBEY = False执行pipelines下的写入操作ITEM_PIPELINES = { 'zhihuuser.pipelines.MongoDBPipeline': 300,}
pipelines.py： 1、首先我们要从settings文件中读取数据的地址、端口、数据库名称（没有会自动创建）。 2、拿到数据库的基本信息后进行连接。 3、将数据写入数据库 4、关闭数据库 注意：只有打开和关闭是只执行一次，而写入操作会根据具体的写入次数而定。
import pymongoclass MongoDBPipeline(object): """ 1、连接数据库操作 """ def __init__(self,mongourl,mongoport,mongodb): ''' 初始化mongodb数据的url、端口号、数据库名称 :param mongourl: :param mongoport: :param mongodb: ''' self.mongourl = mongourl self.mongoport = mongoport self.mongodb = mongodb @classmethod def from_crawler(cls,crawler): """ 1、读取settings里面的mongodb数据的url、port、DB。 :param crawler: :return: """ return cls( mongourl = crawler.settings.get("MONGO_URL"), mongoport = crawler.settings.get("MONGO_PORT"), mongodb = crawler.settings.get("MONGO_DB") ) def open_spider(self,spider): ''' 1、连接mongodb数据 :param spider: :return: ''' self.client = pymongo.MongoClient(self.mongourl,self.mongoport) self.db = self.client[self.mongodb] def process_item(self,item,spider): ''' 1、将数据写入数据库 :param item: :param spider: :return: ''' name = item.__class__.__name__ # self.db[name].insert(dict(item)) self.db['user'].update({'url_token':item['url_token']},{'$set':item},True) return item def close_spider(self,spider): ''' 1、关闭数据库连接 :param spider: :return: ''' self.client.close()