Python Scrapy JSON导出问题

我一直在关注一些在线教程，使用Scrapy来删除Craigslist的电子邮件。我有这段代码，但当我运行命令并导出到json文件时，它会创建该文件，但其中只有一个'['

非常感谢您的帮助。以下是我的代码：

from scrapy.spider import BaseSpider 
from scrapy.selector import HtmlXPathSelector 
from scrapy_demo.items import ScrapyDemoItem
import urlparse 
from scrapy.http.request import Request

class ScrapyDemoSpider(BaseSpider): 
    name = "scrapy_demo"
    allowed_domains = ["buffalo.craigslist.org"]
    start_urls = ['http://buffalo.craigslist.org/search/cps/']

    def parse(self, response):
        hxs = HtmlXPathSelector(response) 
        listings = hxs.select('//....') 
        links = []

        #scrap listings page to get listing links
        for listing in listings:
            link = listing.select('..../@href').extract()[0]
            links.append(link)

        #parse listing url to get content of the listing page
        for link in links:
            item = ScrapyDemoItem()
            item['link'] = link
            yield Request(urlparse.urljoin(response.url, link), meta={'item': item}, callback=self.parse_listing_page)

            #get next button link
            next_page = hxs.select("//..../@href").extract()[0]
            if next_page:
                yield Request(urlparse.urljoin(response.url, next_page), self.parse)

    #scrap listing page to get content
    def parse_listing_page(self, response):
        hxs = HtmlXPathSelector(response)
        item = response.request.meta['item']
        item['title'] = hxs.select('//..../text()').extract()[0]
        item['content'] = hxs.select('//..../text()').extract()[0]
        yield item

这里有很多问题

主要问题是

select（）

调用中的表达式无效

除此之外：

• 使用或不再需要

  HtmlXPathSelector

• 无需在

  parse（）

  回调中实例化

  项

  实例并传入

  meta

  。从

  response.url

  在

  parse\u listing\u page（）中获取url

改进的工作代码：

import urlparse

from scrapy.spider import BaseSpider
from scrapy.http.request import Request

from scrapy_demo.items import ScrapyDemoItem


class ScrapyDemoSpider(BaseSpider): 
    name = "scrapy_demo"
    allowed_domains = ["buffalo.craigslist.org"]
    start_urls = ['http://buffalo.craigslist.org/search/cps/']

    def parse(self, response):
        # processing listings
        for listing in response.css('p.row > a[data-id]'):
            link = listing.xpath('@href').extract()[0]
            yield Request(urlparse.urljoin(response.url, link), callback=self.parse_listing_page)

        # following next page
        next_page = response.xpath('//a[contains(@class, "next")]/@href').extract()
        print next_page
        if next_page:
            yield Request(urlparse.urljoin(response.url, next_page[0]), callback=self.parse)

    def parse_listing_page(self, response):
        item = ScrapyDemoItem()
        item['link'] = response.url
        item['title'] = response.xpath('//title/text()').extract()[0].strip()
        item['content'] = response.xpath('//section[@id="postingbody"]/text()').extract()[0].strip()
        yield item

如果运行spider，那么在输出JSON文件中，您将看到：

[
    {"content": "Using a web cam with your computer to video communicate with your loved ones has never been made easier and it's free (providing you have an Internet connection).  With the click of a few buttons, you are sharing your live video and audio with the person you are communicating with. It's that simple.  When you are seeing and hearing your grand kids live across the country or halfway around the world, web camming is the next best thing to being there!", "link": "http://buffalo.craigslist.org/cps/4784390462.html", "title": "Web Cam With Your Computer With Family And Friends"},
    {"content": "Looking to supplement or increase your earnings?", "link": "http://buffalo.craigslist.org/cps/4782757517.html", "title": "1k in 30 Day's"},
    {"content": "Like us on Facebook: https://www.facebook.com/pages/NFB-Systems/514380315268768", "link": "http://buffalo.craigslist.org/cps/4813039886.html", "title": "NFB SYSTEMS COMPUTER SERVICES + WEB DESIGNING"},
    {"content": "Like us on Facebook: https://www.facebook.com/pages/NFB-Systems/514380315268768", "link": "http://buffalo.craigslist.org/cps/4810219714.html", "title": "NFB Systems Computer Repair + Web Designing"},
    {"content": "I can work with you personally and we design your site together (no outsourcing or anything like that!) I'll even train you how to use your brand new site. (Wordpress is really easy to use once it is setup!)", "link": "http://buffalo.craigslist.org/cps/4792628034.html", "title": "I Make First-Class Wordpress Sites with Training"},
    ...
]