python - 保存网页抓取结果(Scrapy)

Question

我编写了一个似乎运行正常的蜘蛛，但我不确定如何保存它正在收集的数据。

蜘蛛从 TheScienceForum 开始，抓取主要论坛页面并为每个页面创建一个项目。然后，它继续浏览所有单独的论坛页面(将项目与其一起传递)，将每个主题的标题添加到匹配的论坛项目中。代码如下:

from scrapy.spider import BaseSpider
from scrapy.selector import HtmlXPathSelector
from scrapy.contrib.linkextractors.sgml import SgmlLinkExtractor
from scrapy.http import Request

from individualProject.items import ProjectItem

class TheScienceForum(BaseSpider):
    name = "TheScienceForum.com"
    allowed_domains = ["www.thescienceforum.com"]
    start_urls = ["http://www.thescienceforum.com"]
    
    def parse(self, response):
        Sel = HtmlXPathSelector(response)
        forumNames = Sel.select('//h2[@class="forumtitle"]/a/text()').extract()
        items = []
        for forumName in forumNames:
            item = ProjectItem()
            item['name'] = forumName
            items.append(item)
        

        forums = Sel.select('//h2[@class="forumtitle"]/a/@href').extract()
        itemDict = {}
        itemDict['items'] = items
        for forum in forums:
            yield Request(url=forum,meta=itemDict,callback=self.addThreadNames)  

    def addThreadNames(self, response):
        items = response.meta['items']
        Sel = HtmlXPathSelector(response)
        currentForum = Sel.select('//h1/span[@class="forumtitle"]/text()').extract()
        for item in items:
            if currentForum==item['name']:
                item['thread'] += Sel.select('//h3[@class="threadtitle"]/a/text()').extract()
        self.log(items)


        itemDict = {}
        itemDict['items'] = items
        threadPageNavs = Sel.select('//span[@class="prev_next"]/a[@rel="next"]/@href').extract()
        for threadPageNav in threadPageNavs:  
            yield Request(url=threadPageNav,meta=itemDict,callback=self.addThreadNames)

似乎因为我从不简单地返回对象(仅产生新请求)，所以数据永远不会在任何地方持久存在。我尝试使用以下 JSON 管道:

class JsonWriterPipeline(object):

    def __init__(self):
        self.file = open('items.jl', 'wb')

    def process_item(self, item, spider):
        line = json.dumps(dict(item)) + "\n"
        self.file.write(line)
        return item

并且还使用以下命令运行蜘蛛:

scrapy crawl TheScienceForum.com -o items.json -t json

但到目前为止还没有任何效果。我可能哪里出错了？

热烈欢迎任何想法或积极的批评。

Answer 1

您需要在至少一个回调中产生元素。