加载scrapy shell
scrapy shell "http://www.worldfootball.net/all_matches/eng-premier-league-2015-2016/"
尝试选择器：
response.xpath('(//table[@class="standard_tabelle"])[1]/tr[not(th)]')
注意：它打印结果。
但现在将该选择器用作 for 语句：
for row in response.xpath('(//table[@class="standard_tabelle"])[1]/tr[not(th)]'):
row.xpath(".//a[contains(@href, 'report')]/@href").extract_first()
回车两次，什么都没有打印。要在 for 循环中打印结果，您必须将选择器包装在打印函数中。像这样：
print(row.xpath(".//a[contains(@href, 'report')]/@href").extract_first())
为什么？
编辑
如果我做与 Liam 下面的帖子完全相同的事情，我的输出是这样的：
rmp:www rmp$ scrapy shell "http://www.worldfootball.net/all_matches/eng-premier-league-2015-2016/"
2016-03-05 06:13:28 [scrapy] INFO: Scrapy 1.0.5 started (bot: scrapybot)
2016-03-05 06:13:28 [scrapy] INFO: Optional features available: ssl, http11
2016-03-05 06:13:28 [scrapy] INFO: Overridden settings: {'LOGSTATS_INTERVAL': 0, 'DUPEFILTER_CLASS': 'scrapy.dupefilters.BaseDupeFilter'}
2016-03-05 06:13:28 [scrapy] INFO: Enabled extensions: CloseSpider, TelnetConsole, CoreStats, SpiderState
2016-03-05 06:13:28 [scrapy] INFO: Enabled downloader middlewares: HttpAuthMiddleware, DownloadTimeoutMiddleware, UserAgentMiddleware, RetryMiddleware, DefaultHeadersMiddleware, MetaRefreshMiddleware, HttpCompressionMiddleware, RedirectMiddleware, CookiesMiddleware, ChunkedTransferMiddleware, DownloaderStats
2016-03-05 06:13:28 [scrapy] INFO: Enabled spider middlewares: HttpErrorMiddleware, OffsiteMiddleware, RefererMiddleware, UrlLengthMiddleware, DepthMiddleware
2016-03-05 06:13:28 [scrapy] INFO: Enabled item pipelines:
2016-03-05 06:13:28 [scrapy] DEBUG: Telnet console listening on 127.0.0.1:6023
2016-03-05 06:13:28 [scrapy] INFO: Spider opened
2016-03-05 06:13:29 [scrapy] DEBUG: Crawled (200) <GET http://www.worldfootball.net/all_matches/eng-premier-league-2015-2016/> (referer: None)
[s] Available Scrapy objects:
[s] crawler <scrapy.crawler.Crawler object at 0x108c89c10>
[s] item {}
[s] request <GET http://www.worldfootball.net/all_matches/eng-premier-league-2015-2016/>
[s] response <200 http://www.worldfootball.net/all_matches/eng-premier-league-2015-2016/>
[s] settings <scrapy.settings.Settings object at 0x10a25bb10>
[s] spider <DefaultSpider 'default' at 0x10c1201d0>
[s] Useful shortcuts:
[s] shelp() Shell help (print this help)
[s] fetch(req_or_url) Fetch request (or URL) and update local objects
[s] view(response) View response in a browser
2016-03-05 06:13:29 [root] DEBUG: Using default logger
2016-03-05 06:13:29 [root] DEBUG: Using default logger
In [1]: for row in response.xpath('(//table[@class="standard_tabelle"])[1]/tr[not(th)]'):
...: row.xpath(".//a[contains(@href, 'report')]/@href").extract_first()
...:
但是添加了打印？
In [2]: for row in response.xpath('(//table[@class="standard_tabelle"])[1]/tr[not(th)]'):
...: print row.xpath(".//a[contains(@href, 'report')]/@href").extract_first()
...:
/report/premier-league-2015-2016-manchester-united-tottenham-hotspur/
/report/premier-league-2015-2016-afc-bournemouth-aston-villa/
/report/premier-league-2015-2016-everton-fc-watford-fc/
/report/premier-league-2015-2016-leicester-city-sunderland-afc/
/report/premier-league-2015-2016-norwich-city-crystal-palace/