python - Scrapy - 在脚本上下文中打印管道数据

Question

使用 scrapy framework 后，我想在我的 python 脚本中处理我的 pipeline.py 输出上下文。

管道输出为tracks.jl，如下:

管道.py

class PitchforkTracks(object):

    def __init__(self):
        self.file = open('tracks.jl', 'wb')

在同一个script.py目录上生成一个json文件:

    def process_item(self, item, spider):
        line = json.dumps(dict(item)) + "\n"
        self.file.write(line)
        return item

在这里，我运行scrapy。

脚本.py

def output():
    process = CrawlerProcess(get_project_settings())
    response = process.crawl('pitchfork_tracks', domain='pitchfork.com')
    # the script will block here until the crawling is finished
    process.start() 
    #process pipelined file 
    tracks = []
    time.sleep(5)
    #here I pause so there is time for pipeline to build `tracks.jl` at directory
    with open('tracks.jl', 'r+') as t:
        for line in t:
            tracks.append(json.loads(line))
    print (tracks)

    #process lines from here on

但是，当我打印lines时，我得到一个空的list[]。

如何在python脚本内打印pipeline.py的输出？

编辑:

这是我运行scrapy scrappitchfork_tracks时的日志:

2016-10-03 09:28:39 [scrapy] INFO: Scrapy 1.1.2 started (bot: blogs)
2016-10-03 09:28:39 [scrapy] INFO: Overridden settings: {'NEWSPIDER_MODULE': 'blogs.spiders', 'SPIDER_MODULES': ['blogs.spiders'], 'ROBOTSTXT_OBEY': True, 'BOT_NAME': 'blogs'}
2016-10-03 09:28:39 [scrapy] INFO: Enabled extensions:
['scrapy.extensions.logstats.LogStats',
 'scrapy.extensions.telnet.TelnetConsole',
 'scrapy.extensions.corestats.CoreStats']
2016-10-03 09:28:39 [scrapy] INFO: Enabled downloader middlewares:
['scrapy.downloadermiddlewares.robotstxt.RobotsTxtMiddleware',
 'scrapy.downloadermiddlewares.httpauth.HttpAuthMiddleware',
 'scrapy.downloadermiddlewares.downloadtimeout.DownloadTimeoutMiddleware',
 'scrapy.downloadermiddlewares.useragent.UserAgentMiddleware',
 'scrapy.downloadermiddlewares.retry.RetryMiddleware',
 'scrapy.downloadermiddlewares.defaultheaders.DefaultHeadersMiddleware',
 'scrapy.downloadermiddlewares.redirect.MetaRefreshMiddleware',
 'scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware',
 'scrapy.downloadermiddlewares.redirect.RedirectMiddleware',
 'scrapy.downloadermiddlewares.cookies.CookiesMiddleware',
 'scrapy.downloadermiddlewares.chunked.ChunkedTransferMiddleware',
 'scrapy.downloadermiddlewares.stats.DownloaderStats']
2016-10-03 09:28:39 [scrapy] INFO: Enabled spider middlewares:
['scrapy.spidermiddlewares.httperror.HttpErrorMiddleware',
 'scrapy.spidermiddlewares.offsite.OffsiteMiddleware',
 'scrapy.spidermiddlewares.referer.RefererMiddleware',
 'scrapy.spidermiddlewares.urllength.UrlLengthMiddleware',
 'scrapy.spidermiddlewares.depth.DepthMiddleware']
2016-10-03 09:28:39 [scrapy] INFO: Enabled item pipelines:
['blogs.pipelines.PitchforkTracks',
 'blogs.pipelines.PitchforkAlbums',
 'blogs.pipelines.PitchforkReissues']
2016-10-03 09:28:39 [scrapy] INFO: Spider opened
2016-10-03 09:28:39 [scrapy] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min)
2016-10-03 09:28:39 [scrapy] DEBUG: Telnet console listening on 127.0.0.1:6023
2016-10-03 09:28:39 [scrapy] DEBUG: Crawled (200) <GET http://pitchfork.com/robots.txt> (referer: None)
2016-10-03 09:28:40 [scrapy] DEBUG: Crawled (200) <GET http://pitchfork.com/reviews/best/tracks/?page=1> (referer: None)
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Moses Sumney', 'track': u'Lonely World'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Cherry Glazerr', 'track': u"Told You I'd Be With the Guys"}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Danny Brown',
 'track': u'Really Doe\u201d [ft. Kendrick Lamar, Ab-Soul, and Earl Sweatshirt]'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'NxWorries', 'track': u'Lyk Dis'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Nick Cave & the Bad Seeds', 'track': u'I Need You'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Merchandise', 'track': u'Lonesome Sound'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Weyes Blood', 'track': u'Do You Need My Love'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Kelly Lee Owens', 'track': u'CBM'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Sampha', 'track': u'Blood on Me'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Bon Iver', 'track': u'33 \u2018GOD\u2019'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Mick Jenkins', 'track': u'Drowning\u201d [ft. BADBADNOTGOOD]'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Chromatics', 'track': u'Dear Tommy'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Young Thug', 'track': u'Kanye West'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Vince Staples', 'track': u'Prima Donna\u201d [ft. A$AP Rocky]'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Angel Olsen', 'track': u'Sister'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Cass McCombs', 'track': u'Bum Bum Bum'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Hamilton Leithauser', 'track': u'A 1000 Times'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Danny Brown', 'track': u'Pneumonia'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Frank Ocean', 'track': u'Ivy'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Frank Ocean', 'track': u'Rushes'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Half Waif', 'track': u'Turn Me Around'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Rae Sremmurd', 'track': u'Black Beatles\u201d [ft. Gucci Mane]'}
2016-10-03 09:28:40 [scrapy] DEBUG: Scraped from <200 http://pitchfork.com/reviews/best/tracks/?page=1>
{'artist': u'Bon Iver',
 'track': u'22 (OVER S\u221e\u221eN) [Bob Moose Extended Cab Version]'}
2016-10-03 09:28:40 [scrapy] INFO: Closing spider (finished)
2016-10-03 09:28:40 [scrapy] INFO: Dumping Scrapy stats:
{'downloader/request_bytes': 459,
 'downloader/request_count': 2,
 'downloader/request_method_count/GET': 2,
 'downloader/response_bytes': 22624,
 'downloader/response_count': 2,
 'downloader/response_status_count/200': 2,
 'finish_reason': 'finished',
 'finish_time': datetime.datetime(2016, 10, 3, 12, 28, 40, 425137),
 'item_scraped_count': 23,
 'log_count/DEBUG': 26,
 'log_count/INFO': 7,
 'response_received_count': 2,
 'scheduler/dequeued': 1,
 'scheduler/dequeued/memory': 1,
 'scheduler/enqueued': 1,
 'scheduler/enqueued/memory': 1,
 'start_time': datetime.datetime(2016, 10, 3, 12, 28, 39, 535638)}
2016-10-03 09:28:40 [scrapy] INFO: Spider closed (finished)

Answer 1

我认为这是因为您的管道从未关闭文件对象。您应该在管道的 open_spider() 方法中打开文件，并在 close_spider() 方法中关闭它。

class PitchforkTracks(object):

    def open_spider(self, spider):
        self.file = open('tracks.jl', 'wb')

    def close_spider(self, spider):
        self.file.close()

    def process_item(self, item, spider):
        line = json.dumps(dict(item)) + "\n"
        self.file.write(line)
        return item