scrapy爬取网址，进而爬取详情页问题

1、最容易出现的问题是爬取到的url大多为相对路径，如果直接将爬取到的url进行二次爬取就会出现以下报错：

　　raise ValueError('Missing scheme in request url: %s' % self._url)，该错误的意思是request的url为无效链接。

解决方法：将相对路径转换为绝对路径

 # -*- coding: utf-8 -*-
 import scrapy
 from pyquery import PyQuery
 from ..items import City10Item
 from scrapy.http import Request
 from scrapy.utils.response import get_base_url
 from urllib.parse import urljoin

 class CitySpiderTest1Spider(scrapy.Spider):
     name = 'city_spider_test1'
     allowed_domains = ['58.com']
     start_urls = ['https://cq.58.com/chuzu/']

     def parse(self, response):
         jpy=PyQuery(response.text)
         li=jpy('body > div.mainbox > div > div.content > div.listBox > ul > li').items()
         for i in li:
             item=City10Item()
             item['name']=i('div.des > h2 > a').text()
             item['url']=i('div.des > h2 > a').attr('href') #爬取url，此时为相对路径
             item['price']=i('div.listliright > div.money > b').text()
             base_url = get_base_url(response) #获取相对路径前级地址
             abs_url=urljoin(base_url,item['url']) #转换为绝对路径

             if item['url']:
                 yield Request(abs_url,
                               callback=self.detail_parse, #回调详情页函数
                               meta={'item':item}, #将参数传递给meta
                               priority=10,
                               dont_filter=True #强制不过滤

                 )

     def detail_parse(self,response):
         jpy = PyQuery(response.text)
         item = response.meta['item']   #接收item
         item['introduce_item'] = jpy('body > div.main-wrap > div.house-detail-desc > div.main-detail-info.fl > div.house-word-introduce.f16.c_555 > ul > li:nth-child(1) > span.a2').text()   #提取房屋亮点
         item['address'] = jpy('body > div.main-wrap > div.house-basic-info > div.house-basic-right.fr > div.house-basic-desc > div.house-desc-item.fl.c_333 > ul > li:nth-child(6) > span.dz').text()   #房屋详情地址
         item['phone_number'] = jpy('body > div.main-wrap > div.house-basic-info > div.house-basic-right.fr > div.house-fraud-tip > div.house-chat-phone > span').text()   #电话号码
         yield item