python - 我正在尝试使用 Python 3.x 从亚马逊抓取评论，但一无所获

Question

我正在尝试抓取来自亚马逊的所有评论。当我运行下面的代码时，它返回空列表，没有任何错误。我不明白为什么。你能帮我一下吗？

from __future__ import unicode_literals

import requests
from scrapy.selector import Selector

def fetch_page(url):
    r = requests.get(url)
    return r.text 

def  review_positive(url):
    #html = fetch_page(url)
    sel = Selector(text = url)
    review =  sel.css(' .a-section review').extract()
    return review


print (review_positive('https://www.amazon.com/Apple-iPhone-Unlocked-GB-Packaging/product-reviews/B01DAJT1AW/ref=cm_cr_arp_d_viewpnt_lft?ie=UTF8&showViewpoints=1&sortBy=helpful&filterByStar=positive&pageNumber=1'))

Answer 1

CSS 选择器中的类之间不应有空格。相反，使用 . 来分隔类:

.css('.a-section.review').extract()

一旦你解决了这个问题，你的选择器就会正常工作:

In [6]: rev = response.css('.a-section.review').extract()

In [7]: len(rev)
Out[7]: 10

In [8]: rev = response.css('.a-section review').extract()

In [9]: len(rev)
Out[9]: 0