从脚本运行scrapy时不包含管道

Question

我在用一个脚本运行scrapy，但它只启动了爬虫，并没有经过我的数据处理流程。我看过这个链接，但里面没有提到如何包含数据处理流程。

我的设置：

Scraper/
    scrapy.cfg
    ScrapyScript.py
    Scraper/
        __init__.py
        items.py
        pipelines.py
        settings.py
        spiders/
            __init__.py
            my_spider.py

我的脚本：

from twisted.internet import reactor
from scrapy.crawler import Crawler
from scrapy.settings import Settings
from scrapy import log, signals
from Scraper.spiders.my_spider import MySpiderSpider

spider = MySpiderSpider(domain='myDomain.com')
settings = get_project_settings
crawler = Crawler(Settings())
crawler.signals.connect(reactor.stop, signal=signals.spider_closed)
crawler.configure()
crawler.crawl(spider)
crawler.start()
log.start()
log.msg('Reactor activated...')
reactor.run()
log.msg('Reactor stopped.')

我的数据处理流程：

from scrapy.exceptions import DropItem
from scrapy import log
import sqlite3


class ImageCheckPipeline(object):

    def process_item(self, item, spider):
        if item['image']:
            log.msg("Item added successfully.")
            return item
        else:
            del item
            raise DropItem("Non-image thumbnail found: ")


class StoreImage(object):

    def __init__(self):
        self.db = sqlite3.connect('images')
        self.cursor = self.db.cursor()
        try:
            self.cursor.execute('''
                CREATE TABLE IMAGES(IMAGE BLOB, TITLE TEXT, URL TEXT)
            ''')
            self.db.commit()
        except sqlite3.OperationalError:
            self.cursor.execute('''
                DELETE FROM IMAGES
            ''')
            self.db.commit()

    def process_item(self, item, spider):
        title = item['title'][0]
        image = item['image'][0]
        url = item['url'][0]
        self.cursor.execute('''
            INSERT INTO IMAGES VALUES (?, ?, ?)
        ''', (image, title, url))
        self.db.commit()

脚本的输出结果：

[name@localhost Scraper]$ python ScrapyScript.py
2014-08-06 17:55:22-0400 [scrapy] INFO: Reactor activated...
2014-08-06 17:55:22-0400 [my_spider] INFO: Closing spider (finished)
2014-08-06 17:55:22-0400 [my_spider] INFO: Dumping Scrapy stats:
    {'downloader/request_bytes': 213,
     'downloader/request_count': 1,
     'downloader/request_method_count/GET': 1,
     'downloader/response_bytes': 18852,
     'downloader/response_count': 1,
     'downloader/response_status_count/200': 1,
     'finish_reason': 'finished',
     'finish_time': datetime.datetime(2014, 8, 6, 21, 55, 22, 518492),
     'item_scraped_count': 51,
     'response_received_count': 1,
     'scheduler/dequeued': 1,
     'scheduler/dequeued/memory': 1,
     'scheduler/enqueued': 1,
     'scheduler/enqueued/memory': 1,
     'start_time': datetime.datetime(2014, 8, 6, 21, 55, 22, 363898)}
2014-08-06 17:55:22-0400 [my_spider] INFO: Spider closed (finished)
2014-08-06 17:55:22-0400 [scrapy] INFO: Reactor stopped.
[name@localhost Scraper]$ 

Answer 1

我试过@Pawel和文档里的方法，但对我来说不管用。后来我查看了Scrapy的源代码，发现有时候它没有正确识别设置模块。我一直在想为什么管道没有被使用，直到我意识到它们根本没有从脚本中找到。

正如文档和Pawel所说，我使用了：

from scrapy.utils.project import get_project_settings
settings = get_project_settings()
crawler = Crawler(settings)

但是，当我调用：

print "these are the pipelines:"
print crawler.settings.__dict__['attributes']['ITEM_PIPELINES']

时，我得到了：

these are the pipelines:
<SettingsAttribute value={} priority=0>

settings没有被正确填充。

我意识到需要的是一个相对于包含调用Scrapy脚本的模块的项目设置模块的路径，比如scrapy.myproject.settings。然后，我创建了Settings()对象，方法如下：

from scrapy.settings import Settings

settings = Settings()
os.environ['SCRAPY_SETTINGS_MODULE'] = 'scraper.edx_bot.settings'
settings_module_path = os.environ['SCRAPY_SETTINGS_MODULE']
settings.setmodule(settings_module_path, priority='project')

我使用的完整代码，能够有效导入管道，是：

from twisted.internet import reactor
from scrapy.crawler import Crawler
from scrapy import log, signals
from scrapy.settings import Settings
from scrapy.utils.project import get_project_settings
from scrapy.myproject.spiders.first_spider import FirstSpider

spider = FirstSpider()

settings = Settings()
os.environ['SCRAPY_SETTINGS_MODULE'] = 'scrapy.myproject.settings'
settings_module_path = os.environ['SCRAPY_SETTINGS_MODULE']
settings.setmodule(settings_module_path, priority='project')
crawler = Crawler(settings)

crawler.signals.connect(reactor.stop, signal=signals.spider_closed)
crawler.configure()
crawler.crawl(spider)
crawler.start()
log.start(loglevel=log.INFO)
reactor.run()

Answer 2

你需要真正调用一下 get_project_settings。你在代码中传给爬虫的 Settings 对象只会给你一些默认设置，而不是你特定项目的设置。你需要写成这样：

from scrapy.utils.project import get_project_settings
settings = get_project_settings()
crawler = Crawler(settings)