Python Scrapy不断从下一页按钮获取相同的页面链接答案

【问题标题】：Python Scrapy keep getting same page link from next page buttonPython Scrapy不断从下一页按钮获取相同的页面链接
【发布时间】：2017-10-02 08:55:59
【问题描述】：

我正在尝试在 amazon.com 上搜索具有超过 800 条评论的产品链接，但我不断从下一页按钮获取相同的页面链接，它不断返回第 2 页，而我应该得到第 3 页,4 以此类推

我已经设置了一个 IF 条件，将 1,020 之类的审查字符串转换为整数，然后根据访问页面比较是否大于 800

这里是代码

# -*- coding: utf-8 -*-
import scrapy
from amazon.items import AmazonItem
from urlparse import urljoin


class AmazonspiderSpider(scrapy.Spider):
    name = "amazonspider"
    DOWNLOAD_DELAY = 1
    start_urls = ['https://www.amazon.com/s/ref=lp_165993011_nr_n_0?fst=as%3Aoff&rh=n%3A165793011%2Cn%3A%21165795011%2Cn%3A165993011%2Cn%3A2514571011&bbn=165993011&ie=UTF8&qid=1493778423&rnid=165993011']


    def parse(self, response):


        SET_SELECTOR = '.a-carousel-card.acswidget-carousel__card'
        for attr in response.css(SET_SELECTOR):
            #print '\n\n', attr

            item = AmazonItem()

            review_selector = './/*[@class="acs_product-rating__review-count"]/text()'
            link_selector = './/*[@class="a-link-normal"]/@href'

            if attr.xpath(review_selector).extract_first():
                if int(''.join(attr.xpath(review_selector).extract_first().split(','))) >= 800:
                    url = urljoin(response.url, attr.xpath(link_selector).extract_first())
                    item['LINKS'] = url
                    if url:
                        yield scrapy.Request(url, callback=self.parse_link, meta={'item': item})  


            next_page = './/span[@class="pagnRA"]/a[@id="pagnNextLink"]/@href'
            next_page = response.xpath(next_page).extract_first()
            print '\n\n', urljoin(response.url, next_page)
            if next_page:
                yield scrapy.Request(
                    urljoin(response.url, next_page),
                    callback=self.parse
                )
    def parse_link(self, response):

        item = AmazonItem(response.meta['item'])

        catselector = '.cat-link ::text'
        defaultcatselector = '.nav-search-label ::text'
        cat = response.css(catselector).extract_first()
        if cat:
            item['CATAGORY'] = cat
        else:
            item['CATAGORY'] = response.css(defaultcatselector).extract_first()
        return item

这是我在递归调用解析函数之前打印下一页链接时的输出

和

这是页面的下一页选择器的屏幕截图 我哪里出错了？

【问题讨论】：

标签： python html xpath css-selectors scrapy

【解决方案1】：

将下一页代码块移到循环之外。

class AmazonspiderSpider(scrapy.Spider):
name = "amazonspider"
DOWNLOAD_DELAY = 1
start_urls = ['https://www.amazon.com/s/ref=lp_165993011_nr_n_0?fst=as%3Aoff&rh=n%3A165793011%2Cn%3A%21165795011%2Cn%3A165993011%2Cn%3A2514571011&bbn=165993011&ie=UTF8&qid=1493778423&rnid=165993011']


def parse(self, response):


    SET_SELECTOR = '.a-carousel-card.acswidget-carousel__card'
    for attr in response.css(SET_SELECTOR):
        #print '\n\n', attr


        review_selector = './/*[@class="acs_product-rating__review-count"]/text()'
        link_selector = './/*[@class="a-link-normal"]/@href'

        if attr.xpath(review_selector).extract_first():
            if int(''.join(attr.xpath(review_selector).extract_first().split(','))) >= 800:
                url = urljoin(response.url, attr.xpath(link_selector).extract_first())


   next_page = './/span[@class="pagnRA"]/a[@id="pagnNextLink"]/@href'
   next_page = response.xpath(next_page).extract_first()
   print '\n\n', urljoin(response.url, next_page)

   if next_page:
       yield scrapy.Request(
           urljoin(response.url, next_page),
           callback=self.parse
       )

【讨论】：