使用 CrawlerProcess.crawl() 从脚本将 custom_settings 传递给蜘蛛

Question

我正在尝试通过脚本以编程方式调用蜘蛛。我无法使用 CrawlerProcess 通过构造函数覆盖设置。让我用从官方scrapy网站上抓取引号的默认蜘蛛来说明这一点（最后一个代码sn-p在official scrapy quotes example spider）。

class QuotesSpider(Spider):

    name = "quotes"

    def __init__(self, somestring, *args, **kwargs):
        super(QuotesSpider, self).__init__(*args, **kwargs)
        self.somestring = somestring
        self.custom_settings = kwargs


    def start_requests(self):
        urls = [
            'http://quotes.toscrape.com/page/1/',
            'http://quotes.toscrape.com/page/2/',
        ]
        for url in urls:
            yield Request(url=url, callback=self.parse)

    def parse(self, response):
        for quote in response.css('div.quote'):
            yield {
                'text': quote.css('span.text::text').extract_first(),
                'author': quote.css('small.author::text').extract_first(),
                'tags': quote.css('div.tags a.tag::text').extract(),
            }

这是我尝试运行引号蜘蛛的脚本

from scrapy.crawler import CrawlerProcess
from scrapy.utils.project import get_project_settings
from scrapy.settings import Settings

    def main():

    proc = CrawlerProcess(get_project_settings())

    custom_settings_spider = \
    {
        'FEED_URI': 'quotes.csv',
        'LOG_FILE': 'quotes.log'
    }
    proc.crawl('quotes', 'dummyinput', **custom_settings_spider)
    proc.start()

Answer 1

Scrapy 设置有点像 Python 字典。 所以你可以在传递给CrawlerProcess之前更新设置对象：

from scrapy.crawler import CrawlerProcess
from scrapy.utils.project import get_project_settings
from scrapy.settings import Settings

def main():

    s = get_project_settings()
    s.update({
        'FEED_URI': 'quotes.csv',
        'LOG_FILE': 'quotes.log'
    })
    proc = CrawlerProcess(s)

    proc.crawl('quotes', 'dummyinput', **custom_settings_spider)
    proc.start()

---

编辑以下 OP 的 cmets：

这是一个使用 CrawlerRunner 的变体，每次爬网都有一个新的 CrawlerRunner，并在每次迭代时重新配置日志记录以每次写入不同的文件：

import logging
from twisted.internet import reactor, defer

import scrapy
from scrapy.crawler import CrawlerRunner
from scrapy.utils.log import configure_logging, _get_handler
from scrapy.utils.project import get_project_settings


class QuotesSpider(scrapy.Spider):
    name = "quotes"

    def start_requests(self):
        page = getattr(self, 'page', 1)
        yield scrapy.Request('http://quotes.toscrape.com/page/{}/'.format(page),
                             self.parse)

    def parse(self, response):
        for quote in response.css('div.quote'):
            yield {
                'text': quote.css('span.text::text').extract_first(),
                'author': quote.css('small.author::text').extract_first(),
                'tags': quote.css('div.tags a.tag::text').extract(),
            }


@defer.inlineCallbacks
def crawl():
    s = get_project_settings()
    for i in range(1, 4):
        s.update({
            'FEED_URI': 'quotes%03d.csv' % i,
            'LOG_FILE': 'quotes%03d.log' % i
        })

        # manually configure logging for LOG_FILE
        configure_logging(settings=s, install_root_handler=False)
        logging.root.setLevel(logging.NOTSET)
        handler = _get_handler(s)
        logging.root.addHandler(handler)

        runner = CrawlerRunner(s)
        yield runner.crawl(QuotesSpider, page=i)

        # reset root handler
        logging.root.removeHandler(handler)
    reactor.stop()

crawl()
reactor.run() # the script will block here until the last crawl call is finished

Answer 2

我认为您不能在将 Spider 类作为脚本调用时覆盖其 custom_settings 变量，主要是因为设置是在蜘蛛实例化之前加载的。

现在，我没有真正看到具体更改 custom_settings 变量的意义，因为它只是一种覆盖默认设置的方法，而这正是 CrawlerProcess 提供的，这可以按预期工作：

import scrapy
from scrapy.crawler import CrawlerProcess


class MySpider(scrapy.Spider):
    name = 'simple'
    start_urls = ['http://httpbin.org/headers']

    def parse(self, response):
        for k, v in self.settings.items():
            print('{}: {}'.format(k, v))
        yield {
            'headers': response.body
        }

process = CrawlerProcess({
    'USER_AGENT': 'my custom user anget',
    'ANYKEY': 'any value',
})

process.crawl(MySpider)
process.start()

Answer 3

您似乎希望为每个蜘蛛拥有自定义日志。您需要像这样激活日志记录：

from scrapy.utils.log import configure_logging

class MySpider(scrapy.Spider):
    #ommited
    def __init__(self):
        configure_logging({'LOG_FILE' : "logs/mylog.log"})

Answer 4

您可以从命令行覆盖设置

https://doc.scrapy.org/en/latest/topics/settings.html#command-line-options

例如：scrapy crawl myspider -s LOG_FILE=scrapy.log