Question

问题：是否有一种方法可以将BeautifulSoup的html5lib解析器集成到一个scrapy项目中，而不是scrapy的默认lxml解析器中？
Scrapy的解析器在我的抓取页面上（对于某些元素而言）失败。
每20页仅每2页就会发生一次。

作为修复，我将BeautifulSoup的解析器添加到了该项目中（有效）。
就是说，我觉得我要把条件和多个解析器的工作加倍……在某个时候，使用Scrapy解析器的原因是什么？
代码确实有效。。。感觉就像是黑客。
我不是专家，有没有更优雅的方法？

提前多谢

更新：
将中间件类添加到scrapy（来自python软件包scrapy-beautifulsoup）就像是一种魅力。显然，来自Scrapy的lxml不如BeautifulSoup的lxml健壮。我不必求助于html5lib解析器-速度要慢30倍以上。

class BeautifulSoupMiddleware(object):
    def __init__(self, crawler):
        super(BeautifulSoupMiddleware, self).__init__()

        self.parser = crawler.settings.get('BEAUTIFULSOUP_PARSER', "html.parser")

    @classmethod
    def from_crawler(cls, crawler):
        return cls(crawler)

    def process_response(self, request, response, spider):
        """Overridden process_response would "pipe" response.body through BeautifulSoup."""
        return response.replace(body=str(BeautifulSoup(response.body, self.parser)))

原文：

import scrapy
from scrapy.item import Item, Field
from scrapy.loader.processors import TakeFirst, MapCompose
from scrapy import Selector
from scrapy.loader import ItemLoader
from w3lib.html import remove_tags
from bs4 import BeautifulSoup


class SimpleSpider(scrapy.Spider):
    name = 'SimpleSpider'
    allowed_domains = ['totally-above-board.com']
    start_urls = [
        'https://totally-above-board.com/nefarious-scrape-page.html'
    ]

    custom_settings = {
        'ITEM_PIPELINES': {
            'crawler.spiders.simple_spider.Pipeline': 400
        }
    }

    def parse(self, response):
        yield from self.parse_company_info(response)
        yield from self.parse_reviews(response)

    def parse_company_info(self, response):
        print('parse_company_info')
        print('==================')

        loader = ItemLoader(CompanyItem(), response=response)
        loader.add_xpath('company_name',
                         '//h1[contains(@class,"sp-company-name")]//span//text()')

        yield loader.load_item()

    def parse_reviews(self, response):
        print('parse_reviews')
        print('=============')

        # Beautiful Soup
        selector = Selector(response)

        # On the Page (Total Reviews) # 49
        search = '//span[contains(@itemprop,"reviewCount")]//text()'
        review_count = selector.xpath(search).get()
        review_count = int(float(review_count))

        # Number of elements Scrapy's LXML Could find # 0
        search = '//div[@itemprop ="review"]'
        review_element_count =   len(selector.xpath(search))

        # Use Scrapy or Beautiful Soup?
        if review_count > review_element_count:

            # Try Beautiful Soup
            soup = BeautifulSoup(response.text, "lxml")
            root = soup.findAll("div", {"itemprop": "review"})
            for review in root:
                loader = ItemLoader(ReviewItem(), selector=review)
                review_text = review.find("span", {"itemprop": "reviewBody"}).text
                loader.add_value('review_text', review_text)
                author = review.find("span", {"itemprop": "author"}).text
                loader.add_value('author', author)

                yield loader.load_item()
        else:
            # Try Scrapy 
            review_list_xpath = '//div[@itemprop ="review"]'
            selector = Selector(response)
            for review in selector.xpath(review_list_xpath):
                loader = ItemLoader(ReviewItem(), selector=review)
                loader.add_xpath('review_text',
                                 './/span[@itemprop="reviewBody"]//text()')

                loader.add_xpath('author',
                                 './/span[@itemprop="author"]//text()')

                yield loader.load_item()

        yield from self.paginate_reviews(response)

    def paginate_reviews(self, response):
        print('paginate_reviews')
        print('================')

        # Try Scrapy
        selector = Selector(response)
        search = '''//span[contains(@class,"item-next")]
                    //a[@class="next"]/@href
                 '''
        next_reviews_link = selector.xpath(search).get()

        # Try Beautiful Soup
        if next_reviews_link is None:
            soup = BeautifulSoup(response.text, "lxml")
            try:
                next_reviews_link = soup.find("a", {"class": "next"})['href']
            except Exception as e:
                pass


        if next_reviews_link:
            yield response.follow(next_reviews_link, self.parse_reviews)

Answer 1

这是common feature request的Parsel，这是Scrapy抓取XML / HTML的库。

但是，您无需等待此类功能的实施。您可以使用BeautifulSoup修复HTML代码，并在固定的HTML上使用Parsel：

from bs4 import BeautifulSoup

# …

response = response.replace(body=str(BeautifulSoup(response.body, "html5lib")))

可以用Beautiful Soup的html5lib解析器替换Scrapy的默认lxml解析器吗？

1 个答案: