如何在一定数量的请求后停止scrapy蜘蛛? [英] How to stop scrapy spider after certain number of requests?

问题描述

我正在开发一个简单的抓取工具来获取 9 个恶作剧帖子及其图像，但由于一些技术困难，我无法停止抓取工具并继续抓取，这是我不想要的.我想增加计数器值并在 100 个帖子后停止.但是 9gag 页面的设计方式是在每个响应中它只提供 10 个帖子，并且在每次迭代后，我的计数器值重置为 10，在这种情况下，我的循环无限长且永不停止.

I am developing an simple scraper to get 9 gag posts and its images but due to some technical difficulties iam unable to stop the scraper and it keeps on scraping which i dont want.I want to increase the counter value and stop after 100 posts. But the 9gag page was designed in a fashion in each response it gives only 10 posts and after each iteration my counter value resets to 10 in this case my loop runs infintely long and never stops.

# -*- 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 的代码在这里

Code for items.py is here

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错误

So i want to increase a global count value and tried this by passing 3 arguments to parse function it gives error

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

那么有没有办法传递一个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).

So is there a way to pass a global count value and return it after each iteration and stop after 100 posts(suppose).

这里提供了整个项目 Github即使我设置 POST_LIMIT =100 也会发生无限循环，请参阅我执行的命令

Entire project is available here Github Even if i set POST_LIMIT =100 the infinite loop happens,see here command i executed

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

推荐答案

首先:使用 self.count 并在 parse 之外初始化.然后不要阻止项目的解析，而是生成新的请求.看下面的代码:

First: Use self.count and initialize outside of parse. Then don't prevent the parsing of the items, but generating new requests. See the following code:

# -*- 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)

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