Question

我正在尝试使用以下代码从麻省理工学院开放式课程中删除课程信息：

import scrapy

class mitSpider(scrapy.Spider):
    name = 'mitSpider'
    start_urls = ['https://ocw.mit.edu/courses/']

    def parse(self, response):
        for url in response.css('ul li h4 a::attr("href")'):
            yield scrapy.Request(response.url, self.parse_desc)

    def parse_desc(self, response):
        for course_desc in response.css('div#description p::text').extract():
            yield{'Description': course_desc}

但我没有收到任何回报。我得到的输出是（我安装了service_identity，但收到了消息）：

:0 UserWarning: You do not have a working installation of the service_identity module: 
'cannot import name 'opentype''.  
Please install it from <https://pypi.python.org/pypi/service_identity> 
and make sure all of its dependencies are satisfied.  Without the
service_identity module, Twisted can perform only rudimentary TLS client
hostname verification. :0: Many valid certificate/hostname mappings 
may be rejected. 2018-03-21 17:40:14 [scrapy.utils.log] 
INFO: Scrapy 1.5.0 started (bot: mitcrawler)
2018-03-21 17:40:14 [scrapy.utils.log] INFO: 
Versions: lxml 3.7.2.0, libxml2 2.9.4, cssselect 1.0.3, parsel 1.4.0, 
w3lib 1.19.0, Twisted 17.9.0, Python 3.6.0 |Anaconda custom (64-bit)| 
(default, Dec 23 2016, 11:57:41) [MSC v.1900 64 bit (AMD64)], pyOpenSSL 
16.2.0 (OpenSSL 1.0.2k  26 Jan 2017), cryptography 1.7.1, Platform Windows-
10-10.0.16299-SP0 2018-03-21 17:40:14 [scrapy.crawler] 
INFO: Overridden settings: {'BOT_NAME': 'mitcrawler', 'NEWSPIDER_MODULE': 
'mitcrawler.spiders', 'ROBOTSTXT_OBEY': True, 'SPIDER_MODULES': 
['mitcrawler.spiders']}
2018-03-21 17:40:14 [scrapy.middleware] INFO: Enabled extensions:
['scrapy.extensions.corestats.CoreStats',
'scrapy.extensions.telnet.TelnetConsole',
'scrapy.extensions.logstats.LogStats']
2018-03-21 17:40:14 [scrapy.middleware] INFO: Enabled downloader 
middlewares:
['scrapy.downloadermiddlewares.robotstxt.RobotsTxtMiddleware',
'scrapy.downloadermiddlewares.httpauth.HttpAuthMiddleware',
'scrapy.downloadermiddlewares.downloadtimeout.DownloadTimeoutMiddleware',
'scrapy.downloadermiddlewares.defaultheaders.DefaultHeadersMiddleware',
'scrapy.downloadermiddlewares.useragent.UserAgentMiddleware',
'scrapy.downloadermiddlewares.retry.RetryMiddleware',
'scrapy.downloadermiddlewares.redirect.MetaRefreshMiddleware',
'scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware',
'scrapy.downloadermiddlewares.redirect.RedirectMiddleware',
'scrapy.downloadermiddlewares.cookies.CookiesMiddleware',
'scrapy.downloadermiddlewares.httpproxy.HttpProxyMiddleware',
'scrapy.downloadermiddlewares.stats.DownloaderStats']
 2018-03-21 17:40:14 [scrapy.middleware] INFO: Enabled spider middlewares:
['scrapy.spidermiddlewares.httperror.HttpErrorMiddleware',
'scrapy.spidermiddlewares.offsite.OffsiteMiddleware',
'scrapy.spidermiddlewares.referer.RefererMiddleware',
'scrapy.spidermiddlewares.urllength.UrlLengthMiddleware',
 'scrapy.spidermiddlewares.depth.DepthMiddleware']
 2018-03-21 17:40:14 [scrapy.middleware] INFO: Enabled item pipelines:
 []
 2018-03-21 17:40:14 [scrapy.core.engine] INFO: Spider opened
 2018-03-21 17:40:14 [scrapy.extensions.logstats] INFO: Crawled 0 pages (at 0 
pages/min), scraped 0 items (at 0 items/min)
2018-03-21 17:40:14 [scrapy.extensions.telnet] DEBUG: Telnet console 
listening on 127.0.0.1:6023
2018-03-21 17:40:14 [scrapy.core.engine] INFO: Closing spider (finished)
2018-03-21 17:40:14 [scrapy.statscollectors] INFO: Dumping Scrapy stats:
{'finish_reason': 'finished',
'log_count/DEBUG': 1,
'log_count/INFO': 7,
'start_time': datetime.datetime(2018, 3, 21, 6, 40, 14, 762492)}
2018-03-21 17:40:14 [scrapy.core.engine] INFO: Spider closed (finished)

我已尝试按原样运行scrapy网站上提供的示例代码，但它也不起作用。所以问题可能不是代码本身。但我无法弄清楚问题是什么。请帮忙！

Answer 1

您正在尝试重新抓取同一个resonse.url，尝试使用循环中的url：

import scrapy

class mitSpider(scrapy.Spider):
    name = 'mitSpider'
    start_urls = ['https://ocw.mit.edu/courses/']

    def parse(self, response):
        for href in response.css('ul li h4 a::attr(href)'):
            url = response.urljoin(href.extract())
            yield scrapy.Request(url, self.parse_desc)

    def parse_desc(self, response):
        for course_desc in response.css('div#description p::text').extract():
            yield{'Description': course_desc}

使用Scrapy爬行MIT OCW站点，但输出为空

1 个答案: