Question

目前我想从weixin.sogou.com获取一些新闻。但是我遇到了一个问题，即无论我如何更改规则，都不会调用parse_item。

这是我的代码

# -*- coding: utf-8 -*-
import scrapy
from scrapy.linkextractors import LinkExtractor
from scrapy.spiders import CrawlSpider, Rule
class SogouCrawlSpider(CrawlSpider):
    name = 'sogou'
    allowed_domains = ['weixin.sogou.com']
    start_urls = ['http://weixin.sogou.com']

    rules=(
        Rule(
            LinkExtractor(
                restrict_xpaths=('//a')
            ),
            callback="parse_item",follow=False),
    )

    def parse_item(self, response):
        print(response.url)
        yield response.url

运行结果就像

$ scrapy crawl sogou
2018-03-16 23:42:44 [scrapy.utils.log] INFO: Scrapy 1.4.0 started (bot: hotwords_crawler)
2018-03-16 23:42:44 [scrapy.utils.log] INFO: Overridden settings: {'NEWSPIDER_MODULE': 'hotwords_crawler.spiders', 'SPIDER_MODULES': ['hotwords_crawler.spiders'], 'ROBOTSTXT_OBEY': True, 'BOT_NAME': 'hotwords_crawler'}
2018-03-16 23:42:44 [scrapy.middleware] INFO: Enabled extensions:
['scrapy.extensions.memusage.MemoryUsage',
 'scrapy.extensions.logstats.LogStats',
 'scrapy.extensions.telnet.TelnetConsole',
 'scrapy.extensions.corestats.CoreStats']
2018-03-16 23:42:45 [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']
2018-03-16 23:42:45 [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']
2018-03-16 23:42:45 [scrapy.middleware] INFO: Enabled item pipelines:
[]
2018-03-16 23:42:45 [scrapy.core.engine] INFO: Spider opened
2018-03-16 23:42:45 [scrapy.extensions.logstats] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2018-03-16 23:42:45 [scrapy.extensions.telnet] DEBUG: Telnet console listening on 127.0.0.1:6025
2018-03-16 23:42:45 [scrapy.core.engine] DEBUG: Crawled (200) <GET http://weixin.sogou.com/robots.txt> (referer: None)
2018-03-16 23:42:45 [scrapy.downloadermiddlewares.robotstxt] DEBUG: Forbidden by robots.txt: <GET http://weixin.sogou.com>
2018-03-16 23:42:46 [scrapy.core.engine] INFO: Closing spider (finished)
2018-03-16 23:42:46 [scrapy.statscollectors] INFO: Dumping Scrapy stats:
{'downloader/exception_count': 1,
 'downloader/exception_type_count/scrapy.exceptions.IgnoreRequest': 1,
 'downloader/request_bytes': 224,
 'downloader/request_count': 1,
 'downloader/request_method_count/GET': 1,
 'downloader/response_bytes': 975,
 'downloader/response_count': 1,
 'downloader/response_status_count/200': 1,
 'finish_reason': 'finished',
 'finish_time': datetime.datetime(2018, 3, 16, 15, 42, 46, 97869),
 'log_count/DEBUG': 3,
 'log_count/INFO': 7,
 'memusage/max': 34717696,
 'memusage/startup': 34717696,
 'response_received_count': 1,
 'scheduler/dequeued': 1,
 'scheduler/dequeued/memory': 1,
 'scheduler/enqueued': 1,
 'scheduler/enqueued/memory': 1,
 'start_time': datetime.datetime(2018, 3, 16, 15, 42, 45, 497564)}
2018-03-16 23:42:46 [scrapy.core.engine] INFO: Spider closed (finished)

我不知道为什么没有调用parse_item。我真的很困惑如何获取数据。

Answer 1

restrict_xpaths定义了html文件的一部分，没有实际的链接，因此//a正是不要需要放在那里的。

Answer 2

对于链接提取器，最好使用LxmlLinkExtractor，这是推荐的链接提取器，带有方便的过滤选项。它是使用lxml强大的HTMLParser实现的。

使用如下：

# -*- coding: utf-8 -*-
import scrapy
from scrapy.linkextractors import LinkExtractor
from scrapy.spiders import CrawlSpider, Rule
class SogouCrawlSpider(CrawlSpider):
    name = 'sogou'
    allowed_domains = ['weixin.sogou.com']
    start_urls = ['http://weixin.sogou.com']

    rules = (
        Rule(LxmlLinkExtractor(allow=()), callback='parse_item', follow=True),
    )

    def parse_item(self, response):
        print(response.url)
        yield response.url

要控制allow / deny个网址等，您可以在API中找到here

scrapy：没有调用parse_item

2 个答案: