Scrapy不是提取数据，css选择器是正确的。

Question

这是我的第一个刮刀，我有点麻烦。首先，我创建了我的css选择器，它们在使用scrapy时工作。当我运行我的蜘蛛时，它只返回以下内容

2017-10-26 14:48:49 [scrapy.utils.log] INFO: Scrapy 1.4.0 started (bot: digikey)
2017-10-26 14:48:49 [scrapy.utils.log] INFO: Overridden settings: {'BOT_NAME': 'digikey', 'CONCURRENT_REQUESTS': 1, 'NEW
SPIDER_MODULE': 'digikey.spiders', 'SPIDER_MODULES': ['digikey.spiders'], 'USER_AGENT': 'digikey ("Mozilla/5.0 (Windows
NT 6.1; rv:5.0) Gecko/20100101 Firefox/5.02")'}
2017-10-26 14:48:49 [scrapy.middleware] INFO: Enabled extensions:
['scrapy.extensions.corestats.CoreStats',
 'scrapy.extensions.telnet.TelnetConsole',
 'scrapy.extensions.logstats.LogStats']
2017-10-26 14:48:50 [scrapy.middleware] INFO: Enabled downloader middlewares:
['scrapy.downloadermiddlewares.httpauth.HttpAuthMiddleware',
 'scrapy.downloadermiddlewares.downloadtimeout.DownloadTimeoutMiddleware',
 'scrapy.downloadermiddlewares.defaultheaders.DefaultHeadersMiddleware',
 'scrapy.downloadermiddlewares.useragent.UserAgentMiddleware',
 'scrapy.downloadermiddlewares.retry.RetryMiddleware',
 'scrapy.downloadermiddlewares.redirect.MetaRefreshMiddleware',
 'scrapy.downloadermiddlewares.httpcompression.HttpCompressionMiddleware',
 'scrapy.downloadermiddlewares.redirect.RedirectMiddleware',
 'scrapy.downloadermiddlewares.cookies.CookiesMiddleware',
 'scrapy.downloadermiddlewares.httpproxy.HttpProxyMiddleware',
 'scrapy.downloadermiddlewares.stats.DownloaderStats']
2017-10-26 14:48:50 [scrapy.middleware] INFO: Enabled spider middlewares:
['scrapy.spidermiddlewares.httperror.HttpErrorMiddleware',
 'scrapy.spidermiddlewares.offsite.OffsiteMiddleware',
 'scrapy.spidermiddlewares.referer.RefererMiddleware',
 'scrapy.spidermiddlewares.urllength.UrlLengthMiddleware',
 'scrapy.spidermiddlewares.depth.DepthMiddleware']
2017-10-26 14:48:50 [scrapy.middleware] INFO: Enabled item pipelines:
[]
2017-10-26 14:48:50 [scrapy.core.engine] INFO: Spider opened
2017-10-26 14:48:50 [scrapy.extensions.logstats] INFO: Crawled 0 pages (at 0 pages/min), scraped 0 items (at 0 items/min
)
2017-10-26 14:48:50 [scrapy.extensions.telnet] DEBUG: Telnet console listening on 127.0.0.1:6023
2017-10-26 14:48:52 [scrapy.core.engine] DEBUG: Crawled (200) <GET https://www.digikey.com/products/en/capacitors/alumin
um-electrolytic-capacitors/58/page/3?stock=1> (referer: None)
2017-10-26 14:48:52 [scrapy.core.engine] INFO: Closing spider (finished)
2017-10-26 14:48:52 [scrapy.statscollectors] INFO: Dumping Scrapy stats:
{'downloader/request_bytes': 329,
 'downloader/request_count': 1,
 'downloader/request_method_count/GET': 1,
 'downloader/response_bytes': 104631,
 'downloader/response_count': 1,
 'downloader/response_status_count/200': 1,
 'finish_reason': 'finished',
 'finish_time': datetime.datetime(2017, 10, 26, 21, 48, 52, 235020),
 'log_count/DEBUG': 2,
 'log_count/INFO': 7,
 'response_received_count': 1,
 'scheduler/dequeued': 1,
 'scheduler/dequeued/memory': 1,
 'scheduler/enqueued': 1,
 'scheduler/enqueued/memory': 1,
 'start_time': datetime.datetime(2017, 10, 26, 21, 48, 50, 249076)}
2017-10-26 14:48:52 [scrapy.core.engine] INFO: Spider closed (finished)
PS C:\Users\dalla_000\digikey>

我的蜘蛛长得像这样

import scrapy
from scrapy.spiders import CrawlSpider, Rule
from scrapy.linkextractors import LinkExtractor
from digikey.items import DigikeyItem
from scrapy.selector import Selector

class DigikeySpider(CrawlSpider):
    name = 'digikey'
    allowed_domains = ['digikey.com']
    start_urls = ['https://www.digikey.com/products/en/capacitors/aluminum-electrolytic-capacitors/58/page/3?stock=1']

rules = (
    # Extract links matching 'category.php' (but not matching 'subsection.php')
    # and follow links from them (since no callback means follow=True by default).
    Rule(LinkExtractor(allow=('/products/en/capacitors/aluminum-electrolytic-capacitors/58/page/3?stock=1', ), deny=('subsection\.php', ))),
)
def parse_item(self, response):
    for row in response.css('table#productTable tbody tr'):
        item = DigikeyItem()
        item['partnumber'] = row.css('.tr-mfgPartNumber [itemprop="name"]::text').extract_first()
        item['manufacturer'] =  row.css('[itemprop="manufacture"] [itemprop="name"]::text').extract_first()
        item['description'] = row.css('.tr-description::text').extract_first()
        item['quanity'] = row.css('.tr-qtyAvailable::text').extract_first()
        item['price'] = row.css('.tr-unitPrice::text').extract_first()
        item['minimumquanity'] = row.css('.tr-minQty::text').extract_first()
        yield item

        parse_start_url = parse_item

items.py看起来像：

import scrapy


class DigikeyItem(scrapy.Item):
    # define the fields for your item here like:
    # name = scrapy.Field()
    partnumber = scrapy.Field()
    manufacturer = scrapy.Field()
    description = scrapy.Field()
    quanity= scrapy.Field()
    minimumquanity = scrapy.Field()
    price = scrapy.Field()
    pass'

设置：

BOT_NAME = 'digikey'

SPIDER_MODULES = ['digikey.spiders']
NEWSPIDER_MODULE = 'digikey.spiders'


# Crawl responsibly by identifying yourself (and your website) on the user-agent
USER_AGENT = 'digikey ("Mozilla/5.0 (Windows NT 6.1; rv:5.0) Gecko/20100101 Firefox/5.02")'

# Obey robots.txt rules
ROBOTSTXT_OBEY = False

我很难理解为什么没有使用工作的css selectors.Furthermore提取数据，爬行器正在完成工作和关闭。我限制蜘蛛只爬行一页，当它正常工作时，我会为整个网站打开它。

Answer 1

这对我有用(不要更改缩进)：

import scrapy
from scrapy.spiders import CrawlSpider, Rule
from scrapy.linkextractors import LinkExtractor

from scrapy.selector import Selector

class DigikeyItem(scrapy.Item):
    # define the fields for your item here like:
    # name = scrapy.Field()
    partnumber = scrapy.Field()
    manufacturer = scrapy.Field()
    description = scrapy.Field()
    quanity= scrapy.Field()
    minimumquanity = scrapy.Field()
    price = scrapy.Field()

class DigikeySpider(CrawlSpider):
    name = 'digikey'
    allowed_domains = ['digikey.com']
    start_urls = ['https://www.digikey.com/products/en/capacitors/aluminum-electrolytic-capacitors/58/page/3?stock=1']

    rules = (
        # Extract links matching 'category.php' (but not matching 'subsection.php')
        # and follow links from them (since no callback means follow=True by default).
        Rule(LinkExtractor(allow=('/products/en/capacitors/aluminum-electrolytic-capacitors/58/page/3', )),callback='parse_item'),
    )

    def parse_item(self, response):
        for row in response.css('table#productTable tbody tr'):
            item = DigikeyItem()
            item['partnumber'] = row.css('.tr-mfgPartNumber [itemprop="name"]::text').extract_first()
            item['manufacturer'] =  row.css('[itemprop="manufacture"] [itemprop="name"]::text').extract_first()
            item['description'] = row.css('.tr-description::text').extract_first()
            item['quanity'] = row.css('.tr-qtyAvailable::text').extract_first()
            item['price'] = row.css('.tr-unitPrice::text').extract_first()
            item['minimumquanity'] = row.css('.tr-minQty::text').extract_first()
            yield item

    parse_start_url = parse_item

但是，如果要测试规则，请将start_urls更改为

 start_urls = ['https://www.digikey.com/products/en/capacitors/aluminum-electrolytic-capacitors/58']

并删除parse_start_url = parse_item

Answer 2

我认为您不需要使用CrawlSpider，因为创建这个蜘蛛的目的是为了导航一个站点，比如一个论坛或博客，以获取不同类别的帖子或实际项目链接(这就是rules的目的)。

您的rules正在尝试获取不同的url到follow，然后从这些url访问与您的rule匹配的特定url，然后用这些url的响应调用那里指定的方法。

但是在您的示例中，您希望访问start_urls中的特定url，因此CrawlSpider不是这样工作的。您应该只使用Spider实现从start_urls urls获得响应。

class DigikeySpider(scrapy.Spider):
    name = 'digikey'
    allowed_domains = ['digikey.com']
    start_urls = ['https://www.digikey.com/products/en/capacitors/aluminum-electrolytic-capacitors/58/page/3?stock=1']

    def parse(self, response):
        ...