刮擦故障：UnboundLocalError:赋值前引用的局部变量

Question

我正在努力提高我在网络垃圾方面的技能，但我仍然坚持我的脚本。我想在亚马逊上搜集一些信息

以下是我目前的脚本：

import scrapy

from ..items import AmazontutorialItem


class AmazonSpiderSpider(scrapy.Spider):
    name = 'amazon'
    page_number = 2
    start_urls = ['https://www.amazon.com/s?bbn=1&rh=n%3A283155%2Cn%3A%211000%2Cn%3A1%2Cp_n_publication_date%3A1250226011&dc&fst=as%3Aoff&qid=1606224210&rnid=1250225011&ref=lp_1_nr_p_n_publication_date_0']

    def parse(self, response):
        items = AmazontutorialItem()

        product_name = response.css('.a-color-base.a-text-normal::text').extract()
        product_author = response.css('.sg-col-12-of-28 span.a-size-base+ .a-size-base::text').extract()
        product_price = response.css('.a-spacing-top-small .a-price-whole::text').extract()
        product_imagelink = response.css('.s-image::attr(src)').extract()

        items['product_name'] = product_name
        items['product_author'] = product_author
        items['product_price'] = product_price
        items['product_imagelink'] = product_imagelink

        yield items

        next_page = 'https://www.amazon.com/s?i=stripbooks&bbn=1&rh=n%3A283155%2Cn%3A1000%2Cn%3A1%2Cp_n_publication_date%3A1250226011&dc&page=' + str(AmazonSpiderSpider.page_number) + '&fst=as%3Aoff&qid=1606229780&rnid=1250225011&ref=sr_pg_2'
        if AmazonSpiderSpider.page_number <= 3:
            AmazonSpiderSpider += 1
            yield response.follow(next_page, callback = self.parse)

但我得到了这个错误：

UnboundLocalError: local variable 'AmazonSpiderSpider' referenced before assignment

我不明白，我以前从来没有犯过这个错误，即使是网络垃圾

有什么想法吗？谢谢

Answer 1

您正试图从类本身内的类AmazonSpiderSpider访问page_number。您正试图用AmazonSpiderSpider.page_number来实现这一点，这肯定会失败。您打算做的可能是访问self.page_number

以下内容可以解决您的问题：

import scrapy
from ..items import AmazontutorialItem


class AmazonSpiderSpider(scrapy.Spider):
    name = 'amazon'
    page_number = 2
    start_urls = ['https://www.amazon.com/s?bbn=1&rh=n%3A283155%2Cn%3A%211000%2Cn%3A1%2Cp_n_publication_date%3A1250226011&dc&fst=as%3Aoff&qid=1606224210&rnid=1250225011&ref=lp_1_nr_p_n_publication_date_0']

    def parse(self, response):
        items = AmazontutorialItem()

        product_name = response.css('.a-color-base.a-text-normal::text').extract()
        product_author = response.css('.sg-col-12-of-28 span.a-size-base+ .a-size-base::text').extract()
        product_price = response.css('.a-spacing-top-small .a-price-whole::text').extract()
        product_imagelink = response.css('.s-image::attr(src)').extract()

        items['product_name'] = product_name
        items['product_author'] = product_author
        items['product_price'] = product_price
        items['product_imagelink'] = product_imagelink

        yield items

        next_page = 'https://www.amazon.com/s?i=stripbooks&bbn=1&rh=n%3A283155%2Cn%3A1000%2Cn%3A1%2Cp_n_publication_date%3A1250226011&dc&page=' + str(self.page_number) + '&fst=as%3Aoff&qid=1606229780&rnid=1250225011&ref=sr_pg_2'
        if self.page_number <= 3:
            self.page_number += 1
            yield response.follow(next_page, callback = self.parse)