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python - Scrapy LinkExtractor 找不到现有的 url

问题描述

我有一个像这样的爬虫： 

class SkySpider(CrawlSpider):
    name = "spider_v1"
    allowed_domains = [
        "atsu.edu",
    ]

    start_urls = [
        "http://www.atsu.edu",
    ]

    rules = (
        Rule(
            INFO_LINKS_EXTRACTOR,
            follow=True,
            callback='parse_item',
          ),
     )
    def parse_item(self, response):
        print("ENTERED!")
        item = SportsScraperItem()
        item["contact"] = self._parse_contact(response)
        return item

在我的helpers.py 中，我有：

from scrapy.linkextractors import LinkExtractor


def _r(string):
    return f"(.*?)(\b{string}\b)(.*)"


INFO_LINKS_EXTRACTOR = LinkExtractor(
    allow=(
        _r('about'),
    ),
    unique=True,
)

我知道atsu.edu有一个链接https://www.atsu.edu/about-atsu/，但我的提取器似乎没有看到它并且parse_item()方法没有运行。我在这里做错了什么？
编辑 1： 日志：

2019-10-01 15:40:58 [scrapy.core.engine] INFO: Spider opened
2019-10-01 15:40:58 [scrapy.extensions.logstats] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2019-10-01 15:40:58 [steppersspider_v1] INFO: Spider opened: steppersspider_v1
2019-10-01 15:40:58 [scrapy.extensions.telnet] INFO: Telnet console listening on 127.0.0.1:6023
2019-10-01 15:40:59 [scrapy.downloadermiddlewares.redirect] DEBUG: Redirecting (301) to <GET https://www.atsu.edu/robots.txt> from <GET http://WWW.ATSU.EDU/robots.txt>
2019-10-01 15:41:05 [scrapy.core.engine] DEBUG: Crawled (200) <GET https://www.atsu.edu/robots.txt> (referer: None)
2019-10-01 15:41:11 [scrapy.downloadermiddlewares.redirect] DEBUG: Redirecting (301) to <GET https://www.atsu.edu/> from <GET http://WWW.ATSU.EDU>
2019-10-01 15:41:15 [scrapy.core.engine] DEBUG: Crawled (200) <GET https://www.atsu.edu/robots.txt> (referer: None)
2019-10-01 15:41:19 [scrapy.core.engine] DEBUG: Crawled (200) <GET https://www.atsu.edu/> (referer: None)
2019-10-01 15:41:19 [steppersspider_v1] DEBUG: Saved file steppers-www.atsu.edu.html
2019-10-01 15:41:20 [scrapy.core.engine] INFO: Closing spider (finished)
2019-10-01 15:41:20 [scrapy.statscollectors] INFO: Dumping Scrapy stats:

编辑 2
这是我在 regexp101.com 上测试这个正则表达式的方法。

编辑 3
正则表达式的工作函数：

def _r(string):
    return r"^(.*?)(\b{string}\b)(.*)$".format(string=string)

标签： pythonscrapy

解决方案

默认情况下，链接提取器只搜索a和area标签。您正在寻找的链接似乎在li标签中。

您需要tags使用所需的标签将参数传递给链接提取器的构造函数。例如：

tags=('a', 'area', 'li')

请参阅https://doc.scrapy.org/en/latest/topics/link-extractors.html#module-scrapy.linkextractors.lxmlhtml

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