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python - Scrapy 规则如何与爬虫一起使用

coder 2023-05-25 原文

我很难理解爬虫爬虫的规则。我有一个例子不能像我希望的那样工作，所以它可能是两件事:

  1. 我不明白规则是如何运作的。
  2. 我形成了不正确的正则表达式，导致我无法获得所需的结果。

好的，这就是我想要做的:

我想写一个爬虫，它会从 http://www.euroleague.net 获取所有可用的统计信息。网站。 包含我开始所需的所有信息的网站页面是 here .

第 1 步

我在想的第一步是提取“季节”链接并将其搁置。 这里是我打算匹配的 HTML/href(我想一一匹配“季节”部分中的所有链接，但我认为以一个链接为例会更容易):

href="/main/results/by-date?seasoncode=E2001"

这是我为它创建的规则/正则表达式:

Rule(SgmlLinkExtractor(allow=('by-date\?seasoncode\=E\d+',)),follow=True),

第 2 步

当我被蜘蛛带到网页时 http://www.euroleague.net/main/results/by-date?seasoncode=E2001对于第二步，我希望蜘蛛从“常规季节”部分中提取链接。在这种情况下，可以说它应该是“第 1 轮”。我正在寻找的 HTML/href 是:

<a href="/main/results/by-date?seasoncode=E2001&gamenumber=1&phasetypecode=RS"

我构建的规则/正则表达式是:

Rule(SgmlLinkExtractor(allow=('seasoncode\=E\d+\&gamenumber\=\d+\&phasetypecode\=\w+',)),follow=True),

第 3 步

现在我到达页面 (http://www.euroleague.net/main/results/by-date?seasoncode=E2001&gamenumber=1&phasetypecode=RS) 我准备提取指向包含我需要的所有信息的页面的链接: 我正在寻找 HTML/href:

href="/main/results/showgame?gamenumber=1&phasetypecode=RS&gamecode=4&seasoncode=E2001#!boxscore"

我必须遵循的正则表达式是:

Rule(SgmlLinkExtractor(allow=('gamenumber\=\d+\&phasetypecode\=\w+\&gamecode\=\d+\&seasoncode\=E\d+',)),callback='parse_item'),

问题

我认为爬虫应该像这样工作: 规则爬虫就像一个循环。当第一个链接匹配时，爬虫将跟随“步骤 2”页面，而不是“步骤 3”，然后它将提取数据。完成后，它将返回“步骤 1”以匹配第二个链接并再次开始循环到第一步中没有链接的点。

我从终端看到的似乎爬虫在“第 1 步”中循环。它循环遍历所有“步骤 1”链接，但不涉及“步骤 2”/“步骤 3”规则。 

2014-02-28 00:20:31+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?seasoncode=E2000> (referer: http://  www.euroleague.net/main/results/by-date)
2014-02-28 00:20:31+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?seasoncode=E2001> (referer: http://www.euroleague.net/main/results/by-date)
2014-02-28 00:20:31+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?seasoncode=E2002> (referer: http://www.euroleague.net/main/results/by-date)
2014-02-28 00:20:32+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?seasoncode=E2003> (referer: http://www.euroleague.net/main/results/by-date)
2014-02-28 00:20:33+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?seasoncode=E2004> (referer: http://www.euroleague.net/main/results/by-date)

在遍历所有“季节”链接后，它会从我没有看到的链接开始，在我提到的三个步骤中的任何一个中:

http://www.euroleague.net/main/results/by-date?gamenumber=23&phasetypecode=TS++++++++&seasoncode=E2013

只有在“步骤 2”中的所有链接循环而不返回“步骤 1”起点时，才能找到这样的链接结构。

问题是: 规则如何运作？它是一步一步地工作，就像我打算它应该与这个例子一起工作，还是每个规则都有它自己的循环，并且只有在它完成第一个规则的循环后才从一个规则到另一个规则？

这就是我的看法。当然，我的规则/正则表达式可能有问题，而且很有可能。

这就是我从终端得到的所有信息:

scrapy crawl basketsp_test -o item6.xml -t xml
2014-02-28 01:09:20+0200 [scrapy] INFO: Scrapy 0.20.0 started (bot: basketbase)
2014-02-28 01:09:20+0200 [scrapy] DEBUG: Optional features available: ssl, http11, boto, django
2014-02-28 01:09:20+0200 [scrapy] DEBUG: Overridden settings: {'NEWSPIDER_MODULE': 'basketbase.spiders', 'FEED_FORMAT': 'xml', 'SPIDER_MODULES': ['basketbase.spiders'], 'FEED_URI': 'item6.xml', 'BOT_NAME': 'basketbase'}
2014-02-28 01:09:21+0200 [scrapy] DEBUG: Enabled extensions: FeedExporter, LogStats, TelnetConsole, CloseSpider, WebService, CoreStats, SpiderState
2014-02-28 01:09:21+0200 [scrapy] DEBUG: Enabled downloader middlewares: HttpAuthMiddleware, DownloadTimeoutMiddleware, UserAgentMiddleware, RetryMiddleware, DefaultHeadersMiddleware, MetaRefreshMiddleware, HttpCompressionMiddleware, RedirectMiddleware, CookiesMiddleware, ChunkedTransferMiddleware, DownloaderStats
2014-02-28 01:09:21+0200 [scrapy] DEBUG: Enabled spider middlewares: HttpErrorMiddleware, OffsiteMiddleware, RefererMiddleware, UrlLengthMiddleware, DepthMiddleware
2014-02-28 01:09:21+0200 [scrapy] DEBUG: Enabled item pipelines: Basketpipeline3, Basketpipeline1db
2014-02-28 01:09:21+0200 [basketsp_test] INFO: Spider opened
2014-02-28 01:09:21+0200 [basketsp_test] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2014-02-28 01:09:21+0200 [scrapy] DEBUG: Telnet console listening on 0.0.0.0:6023
2014-02-28 01:09:21+0200 [scrapy] DEBUG: Web service listening on 0.0.0.0:6080
2014-02-28 01:09:21+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date> (referer: None)
2014-02-28 01:09:22+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date)
2014-02-28 01:09:22+0200 [basketsp_test] DEBUG: Filtered duplicate request: <GET http://www.euroleague.net/main/results/by-date?seasoncode=E2013> - no more duplicates will be shown (see DUPEFILTER_CLASS)
2014-02-28 01:09:22+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?seasoncode=E2000> (referer: http://www.euroleague.net/main/results/by-date)
2014-02-28 01:09:23+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?seasoncode=E2001> (referer: http://www.euroleague.net/main/results/by-date)
2014-02-28 01:09:23+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?seasoncode=E2002> (referer: http://www.euroleague.net/main/results/by-date)
2014-02-28 01:09:24+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?seasoncode=E2003> (referer: http://www.euroleague.net/main/results/by-date)
2014-02-28 01:09:24+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?seasoncode=E2004> (referer: http://www.euroleague.net/main/results/by-date)
2014-02-28 01:09:25+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?seasoncode=E2005> (referer: http://www.euroleague.net/main/results/by-date)
2014-02-28 01:09:26+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?seasoncode=E2006> (referer: http://www.euroleague.net/main/results/by-date)
2014-02-28 01:09:26+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?seasoncode=E2007> (referer: http://www.euroleague.net/main/results/by-date)
2014-02-28 01:09:27+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?seasoncode=E2008> (referer: http://www.euroleague.net/main/results/by-date)
2014-02-28 01:09:27+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?seasoncode=E2009> (referer: http://www.euroleague.net/main/results/by-date)
2014-02-28 01:09:28+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?seasoncode=E2010> (referer: http://www.euroleague.net/main/results/by-date)
2014-02-28 01:09:29+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?seasoncode=E2011> (referer: http://www.euroleague.net/main/results/by-date)
2014-02-28 01:09:29+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?seasoncode=E2012> (referer: http://www.euroleague.net/main/results/by-date)
2014-02-28 01:09:30+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=24&phasetypecode=TS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:30+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=23&phasetypecode=TS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:31+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=22&phasetypecode=TS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:32+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=21&phasetypecode=TS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:32+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=20&phasetypecode=TS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:33+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=19&phasetypecode=TS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:34+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=18&phasetypecode=TS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:34+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=17&phasetypecode=TS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:35+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=16&phasetypecode=TS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:35+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=15&phasetypecode=TS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:36+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=14&phasetypecode=TS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:37+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=13&phasetypecode=TS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:37+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=12&phasetypecode=TS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:38+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=11&phasetypecode=TS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:39+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=10&phasetypecode=RS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:39+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=9&phasetypecode=RS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:40+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=8&phasetypecode=RS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:40+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=7&phasetypecode=RS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:41+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=6&phasetypecode=RS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:42+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=5&phasetypecode=RS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:42+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=4&phasetypecode=RS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:43+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=3&phasetypecode=RS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:44+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=2&phasetypecode=RS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:44+0200 [basketsp_test] DEBUG: Crawled (200) <GET http://www.euroleague.net/main/results/by-date?gamenumber=1&phasetypecode=RS++++++++&seasoncode=E2013> (referer: http://www.euroleague.net/main/results/by-date?seasoncode=E2013)
2014-02-28 01:09:44+0200 [basketsp_test] INFO: Closing spider (finished)
2014-02-28 01:09:44+0200 [basketsp_test] INFO: Dumping Scrapy stats:
    {'downloader/request_bytes': 13663,
     'downloader/request_count': 39,
     'downloader/request_method_count/GET': 39,
     'downloader/response_bytes': 527838,
     'downloader/response_count': 39,
     'downloader/response_status_count/200': 39,
     'finish_reason': 'finished',
     'finish_time': datetime.datetime(2014, 2, 27, 23, 9, 44, 569579),
     'log_count/DEBUG': 46,
     'log_count/INFO': 3,
     'request_depth_max': 2,
     'response_received_count': 39,
     'scheduler/dequeued': 39,
     'scheduler/dequeued/memory': 39,
     'scheduler/enqueued': 39,
     'scheduler/enqueued/memory': 39,
     'start_time': datetime.datetime(2014, 2, 27, 23, 9, 21, 111255)}
2014-02-28 01:09:44+0200 [basketsp_test] INFO: Spider closed (finished)

这里是爬虫的一个规则部分:

class Basketspider(CrawlSpider):
    name = "basketsp_test"
    download_delay = 0.5

    allowed_domains = ["www.euroleague.net"]
    start_urls = ["http://www.euroleague.net/main/results/by-date"]
    rules = (
        Rule(SgmlLinkExtractor(allow=('by-date\?seasoncode\=E\d+',)),follow=True),
        Rule(SgmlLinkExtractor(allow=('seasoncode\=E\d+\&gamenumber\=\d+\&phasetypecode\=\w+',)),follow=True),
        Rule(SgmlLinkExtractor(allow=('gamenumber\=\d+\&phasetypecode\=\w+\&gamecode\=\d+\&seasoncode\=E\d+',)),callback='parse_item'),



)

最佳答案

你是对的，根据 source code在将每个响应返回给回调函数之前，爬虫从第一个开始循环遍历规则。当您编写规则时，您应该牢记这一点。例如以下规则:

rules(
        Rule(SgmlLinkExtractor(allow=(r'/items',)), callback='parse_item',follow=True),
        Rule(SgmlLinkExtractor(allow=(r'/items/electronics',)), callback='parse_electronic_item',follow=True),
     )

第二条规则永远不会被应用，因为所有的链接都将被第一 strip 有parse_item回调的规则提取出来。 scrapy.dupefilter.RFPDupeFilter 将第二条规则的匹配项作为重复项过滤掉。您应该使用拒绝正确匹配链接:

rules(
        Rule(SgmlLinkExtractor(allow=(r'/items',)), deny=(r'/items/electronics',), callback='parse_item',follow=True),
        Rule(SgmlLinkExtractor(allow=(r'/items/electronics',)), callback='parse_electronic_item',follow=True),
     )

关于python - Scrapy 规则如何与爬虫一起使用，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/22082938/

爬虫pythoneuroleagueby-dateresultsregexweb-crawlerscrapy

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