Question

我正在开发一个简单的刮刀，以获得9个gag的帖子和它的图像，但由于一些技术上的困难，我无法停止刮刀，它继续刮刮我不想要。我想增加计数器值并在100个帖子后停止。但是9gag页面在每个响应中都以一种方式设计，它只提供10个帖子，每次迭代后我的计数器值重置为10，在这种情况下，我的循环运行时间很长，并且永远不会停止。

# -*- coding: utf-8 -*-
import scrapy
from _9gag.items import GagItem

class FirstSpider(scrapy.Spider):
    name = "first"
    allowed_domains = ["9gag.com"]
    start_urls = (
        'http://www.9gag.com/',
    )

    last_gag_id = None
    def parse(self, response):
        count = 0
        for article in response.xpath('//article'):
            gag_id = article.xpath('@data-entry-id').extract()
            count +=1
            if gag_id:
                if (count != 100):
                    last_gag_id = gag_id[0]
                    ninegag_item = GagItem()
                    ninegag_item['entry_id'] = gag_id[0]
                    ninegag_item['url'] = article.xpath('@data-entry-url').extract()[0]
                    ninegag_item['votes'] = article.xpath('@data-entry-votes').extract()[0]
                    ninegag_item['comments'] = article.xpath('@data-entry-comments').extract()[0]
                    ninegag_item['title'] = article.xpath('.//h2/a/text()').extract()[0].strip()
                    ninegag_item['img_url'] = article.xpath('.//div[1]/a/img/@src').extract()

                    yield ninegag_item


                else:
                    break


        next_url = 'http://9gag.com/?id=%s&c=200' % last_gag_id
        yield scrapy.Request(url=next_url, callback=self.parse) 
        print count

items.py代码在这里

from scrapy.item import Item, Field


class GagItem(Item):
    entry_id = Field()
    url = Field()
    votes = Field()
    comments = Field()
    title = Field()
    img_url = Field()

所以我想增加一个全局计数值并尝试通过传递3个参数来解析函数它给出了错误

TypeError: parse() takes exactly 3 arguments (2 given)

那么有没有办法传递全局计数值并在每次迭代后返回它并在100个帖子后停止（假设）。

此处提供整个项目 Github 即使我设置了POST_LIMIT = 100，也会发生无限循环，请参阅此处执行的命令

scrapy crawl first -s POST_LIMIT=10 --output=output.json

Answer 1

有一个内置设置CLOSESPIDER_PAGECOUNT，可以通过命令行-s参数传递或在设置中更改：scrapy crawl <spider> -s CLOSESPIDER_PAGECOUNT=100

一个小小的警告是，如果您启用了缓存，它会将缓存命中计为页数。

Answer 2

首先：使用self.count并在parse之外进行初始化。然后，不要阻止解析项目，而是生成新的requests。请参阅以下代码：

# -*- coding: utf-8 -*-
import scrapy
from scrapy import Item, Field


class GagItem(Item):
    entry_id = Field()
    url = Field()
    votes = Field()
    comments = Field()
    title = Field()
    img_url = Field()


class FirstSpider(scrapy.Spider):

    name = "first"
    allowed_domains = ["9gag.com"]
    start_urls = ('http://www.9gag.com/', )

    last_gag_id = None
    COUNT_MAX = 30
    count = 0

    def parse(self, response):

        for article in response.xpath('//article'):
            gag_id = article.xpath('@data-entry-id').extract()
            ninegag_item = GagItem()
            ninegag_item['entry_id'] = gag_id[0]
            ninegag_item['url'] = article.xpath('@data-entry-url').extract()[0]
            ninegag_item['votes'] = article.xpath('@data-entry-votes').extract()[0]
            ninegag_item['comments'] = article.xpath('@data-entry-comments').extract()[0]
            ninegag_item['title'] = article.xpath('.//h2/a/text()').extract()[0].strip()
            ninegag_item['img_url'] = article.xpath('.//div[1]/a/img/@src').extract()
            self.last_gag_id = gag_id[0]
            self.count = self.count + 1
            yield ninegag_item

        if (self.count < self.COUNT_MAX):
            next_url = 'http://9gag.com/?id=%s&c=10' % self.last_gag_id
            yield scrapy.Request(url=next_url, callback=self.parse)

Answer 3

count是parse()方法的本地方法，因此不会在页面之间保留。将count的所有出现更改为self.count，使其成为类的实例变量，并且它将在页面之间保留。

Answer 4

使用-a option.check link

通过crawl命令传递Spider参数

Answer 5

一个人可以使用custom_settings 如下所示使用CLOSESPIDER_PAGECOUNT。

# -*- coding: utf-8 -*-
import scrapy
from scrapy import Item, Field


class GagItem(Item):
    entry_id = Field()
    url = Field()
    votes = Field()
    comments = Field()
    title = Field()
    img_url = Field()


class FirstSpider(scrapy.Spider):

    name = "first"
    allowed_domains = ["9gag.com"]
    start_urls = ('http://www.9gag.com/', )
    last_gag_id = None

    COUNT_MAX = 30

    custom_settings = {
        'CLOSESPIDER_PAGECOUNT': COUNT_MAX
    }

    def parse(self, response):

        for article in response.xpath('//article'):
            gag_id = article.xpath('@data-entry-id').extract()
            ninegag_item = GagItem()
            ninegag_item['entry_id'] = gag_id[0]
            ninegag_item['url'] = article.xpath('@data-entry-url').extract()[0]
            ninegag_item['votes'] = article.xpath('@data-entry-votes').extract()[0]
            ninegag_item['img_url'] = article.xpath('.//div[1]/a/img/@src').extract()
            self.last_gag_id = gag_id[0]
            yield ninegag_item

            next_url = 'http://9gag.com/?id=%s&c=10' % self.last_gag_id
            yield scrapy.Request(url=next_url, callback=self.parse)

如何在一定数量的请求后停止scrapy蜘蛛？

5 个答案: