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采集的数据存储问题。

# -*- coding: utf-8 -*-

import scrapy
from scrapy import Request
from urllib import parse
import re
from scrapy.spidermiddlewares.httperror import HttpError
from twisted.internet.error import DNSLookupError
from twisted.internet.error import TimeoutError, TCPTimedOutError
import time
from datetime import datetime

from orderspider.items import orderrankitem


class RankingSpider(scrapy.Spider):
    name = 'ranking'
    allowed_domains = ['amazon.com']
    # start_urls = ['https://www.amazon.com/b/ref=sr_aj?node=1045024&bbn=1040660&ajr=0']
    start_urls = ['https://www.amazon.com/s/ref=lp_1040660_ex_n_2?rh=n%3A7141123011%2Cn%3A7147440011%2Cn%3A1040660&bbn=7147440011&ie=UTF8']

    def parse(self, response):
        cate_nodes = response.xpath('//*[@id="leftNav"]/ul[1]/ul/li/span/ul/div/li/span/li/span/ul/div//li//a')
        for list_url in cate_nodes:
            categorys_url = list_url.xpath('@href').extract_first("")
            categorys_name = list_url.xpath('span/text()').extract_first("")
            yield scrapy.Request(url=parse.urljoin(response.url, categorys_url),
                                 meta={"categorys": categorys_name},
                                 callback=self.parse_list, errback=self.errback_http,
                                 dont_filter=True)

    def parse_list(self, response):
        post_nodes = response.xpath('//*[contains(@id,"result_")]/div/div[3]/div[1]')
        for post_url in post_nodes:
            good_url = post_url.xpath('a/@href').extract_first("")
            title = post_url.xpath("a/h2/text()").extract_first("")

            sku_str = '/dp/(.+)/ref'
            sku_obj = re.search(sku_str, good_url)
            if sku_obj:
                sku = sku_obj.group(1)
            regex_str = 'sr=(.+)&nodeID'
            match_obj = re.search(regex_str, good_url)
            if match_obj:
                good_rank = match_obj.group(1).replace("1-", "")
                good_ranks = int(good_rank)
                yield scrapy.Request(url=parse.urljoin(response.url, good_url),
                                     meta={"rank_good": good_ranks, "sku": sku, "title": title, "categorys": response.meta.get("categorys" "")},
                                     callback=self.parse_detail, errback=self.errback_http,
                                     dont_filter=True)

        time.sleep(1)
        next_url = response.css("#pagnNextLink.pagnNext::attr(href)").extract_first("")
        if next_url:
            print(next_url + '%s'.format("下一页"))
            yield Request(url=parse.urljoin(response.url, next_url), callback=self.parse,
                          dont_filter=False)

    def parse_detail(self, response):
        order_rank = orderrankitem()
        time.sleep(1)
        intime = datetime.now().strftime('%Y-%m-%d')
        fit = response.css('#fitRecommendationsLinkRatingText::text').extract_first(default="20%").strip().replace("As expected (", "").replace(")", "")
        asterisk = response.xpath('//*[@id="acrPopover"]/span[1]/a/i[1]/span/text()').extract_first(default="0").strip().replace(" out of 5 stars", "")
        reviews = response.xpath('//*[@id="acrCustomerReviewText"]/text()').extract_first()
        if reviews:
            review_nums = reviews.replace(" customer reviews", "")
        else:
            review_nums = 0
        answered_question = response.xpath('//*[@id="askATFLink"]//span/text()').extract_first()
        if answered_question:
            an_question = int(answered_question.strip().replace(" answered questions", ""))
        else:
            an_question = 0

        order_rank["rank"] = response.meta.get("rank_good", "")
        order_rank["url"] = response.url
        order_rank["title"] = response.meta.get("title", "")
        order_rank["sku"] = response.meta.get("sku", "")
        order_rank["in_time"] = intime
        order_rank["fit"] = fit
        order_rank["asterisk"] = asterisk
        order_rank["categorys"] = response.meta.get("categorys", "")
        order_rank["review_nums"] = review_nums
        order_rank["an_question"] = an_question
        yield order_rank

    def errback_http(self, failure):
        self.logger.error(repr(failure))
        if failure.check(HttpError):
            # these exceptions come from HttpError spider middleware
            # you can get the non-200 response
            response = failure.value.response
            self.logger.error('HttpError on %s', response.url)

        elif failure.check(DNSLookupError):
            # this is the original request
            request = failure.request
            self.logger.error('DNSLookupError on %s', request.url)

        elif failure.check(TimeoutError, TCPTimedOutError):
            request = failure.request
            self.logger.error('TimeoutError on %s', request.url)

老师这是我的代码，有个问题想请教你一下，当我数据采集到第三层的时候，保存的数据总会随机的保存不了，保存了我传进去的默认值。我做了爬虫延时和限速，但是都没有达到预期效果，没有做ip代理, 设置了请求头，请图片描述
请老师忙我看下，这个是什么原因造成的。