在python脚本中将参数传递给scrapy spider [英] Pass argument to scrapy spider within a python script

问题描述

我可以使用来自 wiki 的以下配方在 python 脚本中运行爬行:

I can run crawl in a python script with the following recipe from wiki :

from twisted.internet import reactor
from scrapy.crawler import Crawler
from scrapy import log, signals
from testspiders.spiders.followall import FollowAllSpider
from scrapy.utils.project import get_project_settings

spider = FollowAllSpider(domain='scrapinghub.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()
reactor.run()

如您所见，我可以将 domain 传递给 FollowAllSpider 但我的问题是如何传递 start_urls(实际上是一个date 将被添加到一个固定的 url) 到我的蜘蛛类使用上面的代码?

As you can see i can just pass the domain to FollowAllSpider but my question is that how can i pass the start_urls (actually a date that will been added to a Fixed url)to my spider class using above code?

这是我的蜘蛛类:

class MySpider(CrawlSpider):
    name = 'tw'
    def __init__(self,date):
        y,m,d=date.split('-') #this is a test , it could split with regex! 
        try:
            y,m,d=int(y),int(m),int(d)

        except ValueError:
            raise 'Enter a valid date'

        self.allowed_domains = ['mydomin.com']
        self.start_urls = ['my_start_urls{}-{}-{}'.format(y,m,d)]

    def parse(self, response):
        questions = Selector(response).xpath('//div[@class="result-link"]/span/a/@href') 
        for question in questions:
            item = PoptopItem()
            item['url'] = question.extract()
            yield item['url']

这是我的脚本:

from pdfcreator import convertor
from twisted.internet import reactor
from scrapy.crawler import Crawler
from scrapy import log, signals
#from testspiders.spiders.followall import FollowAllSpider
from scrapy.utils.project import get_project_settings
from poptop.spiders.stackoverflow_spider import MySpider
from poptop.items import PoptopItem

settings = get_project_settings()
crawler = Crawler(settings) 
crawler.signals.connect(reactor.stop, signal=signals.spider_closed)
crawler.configure()

date=raw_input('Enter the date with this format (d-m-Y) : ')
print date
spider=MySpider(date=date)
crawler.crawl(spider)
crawler.start()
log.start()
item=PoptopItem()

for url in item['url']:
    convertor(url)

reactor.run() # the script will block here until the spider_closed signal was sent

如果我只是打印item，我会得到以下错误:

If i just print the item i'll get the following error :

2015-02-25 17:13:47+0330 [tw] ERROR: Spider must return Request, BaseItem or None, got 'unicode' in <GET test-link2015-1-17>

项目:

import scrapy


class PoptopItem(scrapy.Item):
    titles= scrapy.Field()
    content= scrapy.Field()
    url=scrapy.Field()

推荐答案

您需要修改 __init__() 构造函数以接受 date 参数.另外，我会使用 datetime.strptime() 解析日期字符串:

You need to modify your __init__() constructor to accept the date argument. Also, I would use datetime.strptime() to parse the date string:

from datetime import datetime

class MySpider(CrawlSpider):
    name = 'tw'
    allowed_domains = ['test.com']

    def __init__(self, *args, **kwargs):
        super(MySpider, self).__init__(*args, **kwargs) 

        date = kwargs.get('date')
        if not date:
            raise ValueError('No date given')

        dt = datetime.strptime(date, "%m-%d-%Y")
        self.start_urls = ['http://test.com/{dt.year}-{dt.month}-{dt.day}'.format(dt=dt)]

然后，您可以这样实例化蜘蛛:

Then, you would instantiate the spider this way:

spider = MySpider(date='01-01-2015')

或者，你甚至可以完全避免解析日期，首先传递一个 datetime 实例:

Or, you can even avoid parsing the date at all, passing a datetime instance in the first place:

class MySpider(CrawlSpider):
    name = 'tw'
    allowed_domains = ['test.com']

    def __init__(self, *args, **kwargs):
        super(MySpider, self).__init__(*args, **kwargs) 

        dt = kwargs.get('dt')
        if not dt:
            raise ValueError('No date given')

        self.start_urls = ['http://test.com/{dt.year}-{dt.month}-{dt.day}'.format(dt=dt)]

spider = MySpider(dt=datetime(year=2014, month=01, day=01))

而且，仅供参考，请参阅此答案作为关于如何从脚本运行 Scrapy.

And, just FYI, see this answer as a detailed example about how to run Scrapy from script.

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