scrapy ValueError("url 不能為 None")

Question

我正在嘗試編寫一個獲取名稱、gdp 和國家出生和死亡值的蜘蛛，但在處理起始 url 時我找不到錯誤在哪里或錯誤的解決方案，不知道這是否是一個問題對於 xpath 或其他東西，我發現的大多數線程都在談論錯誤的縮進，但這不是我的情況。

代碼：

import scrapy
import logging

class GdpsSpider(scrapy.Spider):

name = 'gdps'
allowed_domains = ['www.worldpopulationreview.com']
start_urls = ['https://worldpopulationreview.com/countries/countries-by-national-debt/']

def parse(self, response):
    countries = response.xpath('//tr')
    for country in countries:
        name = country.xpath(".//td[1]/a/text()").get()
        link = country.xpath(".//td[1]/a/@href").get()
        gdp = country.xpath(".//td[2]/text()").get()

        # yield{
        #     'name': name,
        #     'gdp': gdp,
        #     'link': link
        # }

        yield response.follow(url=link, callback=self.parse_bd, meta={'name':name, 'gdp':gdp})

def parse_bd(self, response):
    name = response.request.meta['name']
    gdp = response.request.meta['gdp']

    # rows = response.xpath('//*[@id="popClock"]/div/div[1]/div/div/table/tbody')

    rows = response.xpath("(//table[@class='table table-striped'])[1]/tbody")
    for row in rows:
        births = row.xpath(".//tr[3]/td[@class='number']/text()").get()
        deaths = row.xpath(".//tr[4]/td[@class='number']/text()").get()

        yield{
            'name': name,
            'gdp': gdp,
            'births': births,
            'deaths': deaths
        }

錯誤：

(virtual_workspace) C:\Users\Bugra\projects\gdp>scrapy crawl gdps
2022-04-12 21:43:57 [scrapy.utils.log] INFO: Scrapy 2.6.1 started (bot: gdp)
2022-04-12 21:43:57 [scrapy.utils.log] INFO: Versions: lxml 4.8.0.0, libxml2 2.9.10, cssselect 1.1.0, parsel 1.6.0, w3lib 1.22.0, Twisted 22.2.0, Python 3.9.12 (main, Apr  4 2022, 05:22:27) [MSC v.1916 64 bit (AMD64)], pyOpenSSL 22.0.0 (OpenSSL 1.1.1n  15 Mar 2022), cryptography 36.0.2, Platform Windows-10-10.0.22000-SP0
2022-04-12 21:43:57 [scrapy.crawler] INFO: Overridden settings:
{'BOT_NAME': 'gdp',
 'NEWSPIDER_MODULE': 'gdp.spiders',
 'ROBOTSTXT_OBEY': True,
 'SPIDER_MODULES': ['gdp.spiders']}
2022-04-12 21:43:57 [scrapy.utils.log] DEBUG: Using reactor: twisted.internet.selectreactor.SelectReactor
2022-04-12 21:43:57 [scrapy.extensions.telnet] INFO: Telnet Password: 10f8998db04ef71d
2022-04-12 21:43:57 [scrapy.middleware] INFO: Enabled extensions:
['scrapy.extensions.corestats.CoreStats',
 'scrapy.extensions.telnet.TelnetConsole',
 'scrapy.extensions.logstats.LogStats']
2022-04-12 21:43:57 [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']
2022-04-12 21:43:57 [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']
2022-04-12 21:43:57 [scrapy.middleware] INFO: Enabled item pipelines:
[]
2022-04-12 21:43:57 [scrapy.core.engine] INFO: Spider opened
2022-04-12 21:43:57 [scrapy.extensions.logstats] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2022-04-12 21:43:57 [scrapy.extensions.telnet] INFO: Telnet console listening on 127.0.0.1:6023
2022-04-12 21:43:58 [scrapy.downloadermiddlewares.redirect] DEBUG: Redirecting (307) to <GET https://worldpopulationreview.com/robots.txt> from <GET https://www.worldpopulationreview.com/robots.txt>
2022-04-12 21:43:58 [py.warnings] WARNING: C:\Users\Bugra\anaconda3\envs\virtual_workspace\lib\site-packages\scrapy\core\engine.py:276: ScrapyDeprecationWarning: Passing a 'spider' argument to ExecutionEngine.download is deprecated
  return self.download(result, spider) if isinstance(result, Request) else result

2022-04-12 21:43:58 [scrapy.core.engine] DEBUG: Crawled (404) <GET https://worldpopulationreview.com/robots.txt> (referer: None)
2022-04-12 21:43:58 [protego] DEBUG: Rule at line 1 without any user agent to enforce it on.
2022-04-12 21:43:58 [scrapy.downloadermiddlewares.redirect] DEBUG: Redirecting (307) to <GET https://worldpopulationreview.com/countries/countries-by-national-debt/> from <GET https://www.worldpopulationreview.com/countries/countries-by-national-debt/>
2022-04-12 21:43:58 [scrapy.core.engine] DEBUG: Crawled (404) <GET https://worldpopulationreview.com/robots.txt> (referer: None)
2022-04-12 21:43:58 [protego] DEBUG: Rule at line 1 without any user agent to enforce it on.
2022-04-12 21:43:58 [scrapy.downloadermiddlewares.redirect] DEBUG: Redirecting (308) to <GET https://worldpopulationreview.com/countries/countries-by-national-debt> from <GET https://worldpopulationreview.com/countries/countries-by-national-debt/>
2022-04-12 21:43:58 [scrapy.core.engine] DEBUG: Crawled (200) <GET https://worldpopulationreview.com/countries/countries-by-national-debt> (referer: None)
2022-04-12 21:43:58 [scrapy.core.scraper] ERROR: Spider error processing <GET https://worldpopulationreview.com/countries/countries-by-national-debt> (referer: None)
Traceback (most recent call last):
  File "C:\Users\Bugra\anaconda3\envs\virtual_workspace\lib\site-packages\scrapy\utils\defer.py", line 132, in iter_errback
    yield next(it)
  File "C:\Users\Bugra\anaconda3\envs\virtual_workspace\lib\site-packages\scrapy\utils\python.py", line 354, in __next__
    return next(self.data)
  File "C:\Users\Bugra\anaconda3\envs\virtual_workspace\lib\site-packages\scrapy\utils\python.py", line 354, in __next__
    return next(self.data)
  File "C:\Users\Bugra\anaconda3\envs\virtual_workspace\lib\site-packages\scrapy\core\spidermw.py", line 66, in _evaluate_iterable
    for r in iterable:
  File "C:\Users\Bugra\anaconda3\envs\virtual_workspace\lib\site-packages\scrapy\spidermiddlewares\offsite.py", line 29, in process_spider_output
    for x in result:
  File "C:\Users\Bugra\anaconda3\envs\virtual_workspace\lib\site-packages\scrapy\core\spidermw.py", line 66, in _evaluate_iterable
    for r in iterable:
  File "C:\Users\Bugra\anaconda3\envs\virtual_workspace\lib\site-packages\scrapy\spidermiddlewares\referer.py", line 342, in <genexpr>
    return (_set_referer(r) for r in result or ())
  File "C:\Users\Bugra\anaconda3\envs\virtual_workspace\lib\site-packages\scrapy\core\spidermw.py", line 66, in _evaluate_iterable
    for r in iterable:
  File "C:\Users\Bugra\anaconda3\envs\virtual_workspace\lib\site-packages\scrapy\spidermiddlewares\urllength.py", line 40, in <genexpr>
    return (r for r in result or () if _filter(r))
  File "C:\Users\Bugra\anaconda3\envs\virtual_workspace\lib\site-packages\scrapy\core\spidermw.py", line 66, in _evaluate_iterable
    for r in iterable:
  File "C:\Users\Bugra\anaconda3\envs\virtual_workspace\lib\site-packages\scrapy\spidermiddlewares\depth.py", line 58, in <genexpr>
    return (r for r in result or () if _filter(r))
  File "C:\Users\Bugra\anaconda3\envs\virtual_workspace\lib\site-packages\scrapy\core\spidermw.py", line 66, in _evaluate_iterable
    for r in iterable:
  File "C:\Users\Bugra\projects\gdp\gdp\spiders\gdps.py", line 22, in parse
    yield response.follow(url=link, callback=self.parse_bd, meta={'name':name, 'gdp':gdp})
  File "C:\Users\Bugra\anaconda3\envs\virtual_workspace\lib\site-packages\scrapy\http\response\text.py", line 158, in follow
    return super().follow(
  File "C:\Users\Bugra\anaconda3\envs\virtual_workspace\lib\site-packages\scrapy\http\response\__init__.py", line 163, in follow
    raise ValueError("url can't be None")
ValueError: url can't be None
2022-04-12 21:43:58 [scrapy.core.engine] INFO: Closing spider (finished)
2022-04-12 21:43:58 [scrapy.statscollectors] INFO: Dumping Scrapy stats:
{'downloader/request_bytes': 1522,
 'downloader/request_count': 6,
 'downloader/request_method_count/GET': 6,
 'downloader/response_bytes': 17956,
 'downloader/response_count': 6,
 'downloader/response_status_count/200': 1,
 'downloader/response_status_count/307': 2,
 'downloader/response_status_count/308': 1,
 'downloader/response_status_count/404': 2,
 'elapsed_time_seconds': 1.021947,
 'finish_reason': 'finished',
 'finish_time': datetime.datetime(2022, 4, 12, 18, 43, 58, 619959),
 'httpcompression/response_bytes': 56201,
 'httpcompression/response_count': 3,
 'log_count/DEBUG': 9,
 'log_count/ERROR': 1,
 'log_count/INFO': 10,
 'log_count/WARNING': 1,
 'response_received_count': 3,
 'robotstxt/request_count': 2,
 'robotstxt/response_count': 2,
 'robotstxt/response_status_count/404': 2,
 'scheduler/dequeued': 3,
 'scheduler/dequeued/memory': 3,
 'scheduler/enqueued': 3,
 'scheduler/enqueued/memory': 3,
 'spider_exceptions/ValueError': 1,
 'start_time': datetime.datetime(2022, 4, 12, 18, 43, 57, 598012)}
2022-04-12 21:43:58 [scrapy.core.engine] INFO: Spider closed (finished)

Answer 1

我剛剛弄明白了。 我更改了允許的域

allowed_domains = ['www.worldpopulationreview.com']

到

allowed_domains = ['worldpopulationreview.com']

allowed domains 只接受域而不是 URL。