运行环境：
* Python 2.7.12  
* Scrapy 1.2.2
* Mac OS X 10.10.3 Yosemite

继续爬取Scrapy 1.2.2文档提供的练习网址：

“http://quotes.toscrapy.com“

可以暂时不用考虑爬虫被封的情况，用于初级爬虫练习。

目标

多级页面爬取时，在什么位置yield items是个问题，结论是可以放入子页面的爬取时yield items。但是要记住scrapy的自动去重。

最终代码

因为本次实验内容较多。因此先给出最终的代码。

items.py声明items

增加声明子页面的抓取内容。

import scrapy


class QuotesItem(scrapy.Item):
    quote = scrapy.Field()
    author = scrapy.Field()
    tags = scrapy.Field()

    author_born_date = scrapy.Field()
    author_born_location = scrapy.Field()
    author_description = scrapy.Field()
    author_full_url = scrapy.Field()

爬虫文件

需要进行以下关键内容改写：

• 引入items.py中的类
• 更改爬虫名
• 把作者的介绍页面的链接（author_full_url）放入items中。
• 需要把item的元数据传入子页面的request中：meta={'item':item}
• 需要把Scrapy的自动去重机制关掉：callback=self.parse_author,dont_filter=True

最终代码如下：

import scrapy
from quotes_2.items import QuotesItem

class QuotesSpider(scrapy.Spider):
    name = 'quotes_2_6'
    start_urls = [
        'http://quotes.toscrape.com',
    ]
    allowed_domains = [
        'toscrape.com',
    ]

    def parse(self,response):
        for quote in response.css('div.quote'):
            item = QuotesItem()
            item['quote'] = quote.css('span.text::text').extract_first()
            item['author'] = quote.css('small.author::text').extract_first()
            item['tags'] = quote.css('div.tags a.tag::text').extract()
            author_page = response.css('small.author+a::attr(href)').extract_first()
            item['author_full_url'] = response.urljoin(author_page)
            


            yield scrapy.Request(url=item['authro_full_url'], meta={'item':item},callback=self.parse_author,dont_filter=True)
        
        next_page = response.css('li.next a::attr("href")').extract_first()
        if next_page is not None:
            next_full_url = response.urljoin(next_page)
            yield scrapy.Request(next_full_url, callback=self.parse)            



    def parse_author(self,response):
        item = response.meta['item']
        item['author_born_date'] = response.css('.author-born-date::text').extract_first()
        item['author_born_location'] = response.css('.author-born-location::text').extract_first()
        item['author_description'] = response.css('.author-born-location::text').extract_first()        
        yield item

实验内容记录

步骤1：声明items

首先，我们针对进行改写。

爬虫文件在改写前的原始文件如下：

import scrapy

class QuotesSpider(scrapy.Spider):
    name = 'quotes_2_3'
    start_urls = [
        'http://quotes.toscrape.com',
    ]
    allowed_domains = [
        'toscrape.com',
    ]

    def parse(self,response):
        for quote in response.css('div.quote'):
            yield{
                'quote': quote.css('span.text::text').extract_first(),
                'author': quote.css('small.author::text').extract_first(),
                'tags': quote.css('div.tags a.tag::text').extract(),
            }
            author_page = response.css('small.author+a::attr(href)').extract_first()
            authro_full_url = response.urljoin(author_page)
            yield scrapy.Request(authro_full_url, callback=self.parse_author)


    def parse_author(self,response):
        yield{
            'author': response.css('.author-title::text').extract_first(),
            'author_born_date': response.css('.author-born-date::text').extract_first(),
            'author_born_location': response.css('.author-born-location::text').extract_first(),
            'authro_description': response.css('.author-born-location::text').extract_first(),
        }

把子页面下要爬取的内容也声明items。

import scrapy


class QuotesItem(scrapy.Item):
    quote = scrapy.Field()
    author = scrapy.Field()
    tags = scrapy.Field()

# For author introductions
    author_born_date = scrapy.Field()
    author_born_location = scrapy.Field()
    author_description = scrapy.Field()

步骤2：爬虫

在子页面再yield item

import scrapy
from quotes_2.items import QuotesItem

class QuotesSpider(scrapy.Spider):
    name = 'quotes_2_5'
    start_urls = [
        'http://quotes.toscrape.com',
    ]
    allowed_domains = [
        'toscrape.com',
    ]

    def parse(self,response):
        for quote in response.css('div.quote'):
            item = QuotesItem()
            item['quote'] = quote.css('span.text::text').extract_first()
            item['author'] = quote.css('small.author::text').extract_first()
            item['tags'] = quote.css('div.tags a.tag::text').extract()
            

            author_page = response.css('small.author+a::attr(href)').extract_first()
            author_full_url = response.urljoin(author_page)
            yield scrapy.Request(authro_full_url, meta={'item':item},callback=self.parse_author)
            

    def parse_author(self,response):
        item = response.meta['item']
        item['author_born_date'] = response.css('.author-born-date::text').extract_first()
        item['author_born_location'] = response.css('.author-born-location::text').extract_first()
        item['author_description'] = response.css('.author-born-location::text').extract_first()        
        yield item

结果

[
{"author_description": "in Ulm, Germany", "author": "Albert Einstein", "quote": "\u201cThe world as we have created it is a process of our thinking. It cannot be changed without changing our thinking.\u201d", "tags": ["change", "deep-thoughts", "thinking", "world"], "author_born_date": "March 14, 1879", "author_born_location": "in Ulm, Germany"}
]

parse()函数以及子页面同时yield item

import scrapy
from quotes_2.items import QuotesItem

class QuotesSpider(scrapy.Spider):
    name = 'quotes_2_5'
    start_urls = [
        'http://quotes.toscrape.com',
    ]
    allowed_domains = [
        'toscrape.com',
    ]

    def parse(self,response):
        for quote in response.css('div.quote'):
            item = QuotesItem()
            item['quote'] = quote.css('span.text::text').extract_first()
            item['author'] = quote.css('small.author::text').extract_first()
            item['tags'] = quote.css('div.tags a.tag::text').extract()
            yield item

            author_page = response.css('small.author+a::attr(href)').extract_first()
            author_full_url = response.urljoin(author_page)
            yield scrapy.Request(authro_full_url, meta={'item':item},callback=self.parse_author)
            

    def parse_author(self,response):
        item = response.meta['item']
        item['author_born_date'] = response.css('.author-born-date::text').extract_first()
        item['author_born_location'] = response.css('.author-born-location::text').extract_first()
        item['author_description'] = response.css('.author-born-location::text').extract_first()        
        yield item

json文件结果

[
{"quote": "\u201cThe world as we have created it is a process of our thinking. It cannot be changed without changing our thinking.\u201d", "author": "Albert Einstein", "tags": ["change", "deep-thoughts", "thinking", "world"]},
{"quote": "\u201cIt is our choices, Harry, that show what we truly are, far more than our abilities.\u201d", "author": "J.K. Rowling", "tags": ["abilities", "choices"]},
{"quote": "\u201cThere are only two ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle.\u201d", "author": "Albert Einstein", "tags": ["inspirational", "life", "live", "miracle", "miracles"]},
{"quote": "\u201cThe person, be it gentleman or lady, who has not pleasure in a good novel, must be intolerably stupid.\u201d", "author": "Jane Austen", "tags": ["aliteracy", "books", "classic", "humor"]},
{"quote": "\u201cImperfection is beauty, madness is genius and it's better to be absolutely ridiculous than absolutely boring.\u201d", "author": "Marilyn Monroe", "tags": ["be-yourself", "inspirational"]},
{"quote": "\u201cTry not to become a man of success. Rather become a man of value.\u201d", "author": "Albert Einstein", "tags": ["adulthood", "success", "value"]},
{"quote": "\u201cIt is better to be hated for what you are than to be loved for what you are not.\u201d", "author": "Andr\u00e9 Gide", "tags": ["life", "love"]},
{"quote": "\u201cI have not failed. I've just found 10,000 ways that won't work.\u201d", "author": "Thomas A. Edison", "tags": ["edison", "failure", "inspirational", "paraphrased"]},
{"quote": "\u201cA woman is like a tea bag; you never know how strong it is until it's in hot water.\u201d", "author": "Eleanor Roosevelt", "tags": ["misattributed-eleanor-roosevelt"]},
{"quote": "\u201cA day without sunshine is like, you know, night.\u201d", "author": "Steve Martin", "tags": ["humor", "obvious", "simile"]},
{"author_description": "in Ulm, Germany", "author": "Albert Einstein", "quote": "\u201cThe world as we have created it is a process of our thinking. It cannot be changed without changing our thinking.\u201d", "tags": ["change", "deep-thoughts", "thinking", "world"], "author_born_date": "March 14, 1879", "author_born_location": "in Ulm, Germany"}
]

把作者介绍页面放入items中

如下：

    def parse(self,response):
        for quote in response.css('div.quote'):
            item = QuotesItem()
            item['quote'] = quote.css('span.text::text').extract_first()
            item['author'] = quote.css('small.author::text').extract_first()
            item['tags'] = quote.css('div.tags a.tag::text').extract()
            yield item

            author_page = response.css('small.author+a::attr(href)').extract_first()
            item['authro_full_url'] = response.urljoin(author_page)
            yield scrapy.Request(url=item['authro_full_url'], meta={'item':item},callback=self.parse_author)

得到json文件，仍然只有一个作者。

[
{"quote": "\u201cThe world as we have created it is a process of our thinking. It cannot be changed without changing our thinking.\u201d", "author": "Albert Einstein", "tags": ["change", "deep-thoughts", "thinking", "world"]},
{"quote": "\u201cIt is our choices, Harry, that show what we truly are, far more than our abilities.\u201d", "author": "J.K. Rowling", "tags": ["abilities", "choices"]},
{"quote": "\u201cThere are only two ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle.\u201d", "author": "Albert Einstein", "tags": ["inspirational", "life", "live", "miracle", "miracles"]},
{"quote": "\u201cThe person, be it gentleman or lady, who has not pleasure in a good novel, must be intolerably stupid.\u201d", "author": "Jane Austen", "tags": ["aliteracy", "books", "classic", "humor"]},
{"quote": "\u201cImperfection is beauty, madness is genius and it's better to be absolutely ridiculous than absolutely boring.\u201d", "author": "Marilyn Monroe", "tags": ["be-yourself", "inspirational"]},
{"quote": "\u201cTry not to become a man of success. Rather become a man of value.\u201d", "author": "Albert Einstein", "tags": ["adulthood", "success", "value"]},
{"quote": "\u201cIt is better to be hated for what you are than to be loved for what you are not.\u201d", "author": "Andr\u00e9 Gide", "tags": ["life", "love"]},
{"quote": "\u201cI have not failed. I've just found 10,000 ways that won't work.\u201d", "author": "Thomas A. Edison", "tags": ["edison", "failure", "inspirational", "paraphrased"]},
{"quote": "\u201cA woman is like a tea bag; you never know how strong it is until it's in hot water.\u201d", "author": "Eleanor Roosevelt", "tags": ["misattributed-eleanor-roosevelt"]},
{"quote": "\u201cA day without sunshine is like, you know, night.\u201d", "author": "Steve Martin", "tags": ["humor", "obvious", "simile"]},
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "author": "Albert Einstein", "quote": "\u201cThe world as we have created it is a process of our thinking. It cannot be changed without changing our thinking.\u201d", "tags": ["change", "deep-thoughts", "thinking", "world"], "author_born_date": "March 14, 1879", "author_born_location": "in Ulm, Germany", "author_description": "in Ulm, Germany"}
]

把作者页面先放进items再yield

    def parse(self,response):
        for quote in response.css('div.quote'):
            item = QuotesItem()
            item['quote'] = quote.css('span.text::text').extract_first()
            item['author'] = quote.css('small.author::text').extract_first()
            item['tags'] = quote.css('div.tags a.tag::text').extract()
            author_page = response.css('small.author+a::attr(href)').extract_first()
            item['authro_full_url'] = response.urljoin(author_page)
            yield item


            yield scrapy.Request(url=item['authro_full_url'], meta={'item':item},callback=self.parse_author)
            
    def parse_author(self,response):
        item = response.meta['item']
        item['author_born_date'] = response.css('.author-born-date::text').extract_first()
        item['author_born_location'] = response.css('.author-born-location::text').extract_first()
        item['author_description'] = response.css('.author-born-location::text').extract_first()        
        yield item
        

结果

[
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "quote": "\u201cThe world as we have created it is a process of our thinking. It cannot be changed without changing our thinking.\u201d", "author": "Albert Einstein", "tags": ["change", "deep-thoughts", "thinking", "world"]},
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "quote": "\u201cIt is our choices, Harry, that show what we truly are, far more than our abilities.\u201d", "author": "J.K. Rowling", "tags": ["abilities", "choices"]},
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "quote": "\u201cThere are only two ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle.\u201d", "author": "Albert Einstein", "tags": ["inspirational", "life", "live", "miracle", "miracles"]},
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "quote": "\u201cThe person, be it gentleman or lady, who has not pleasure in a good novel, must be intolerably stupid.\u201d", "author": "Jane Austen", "tags": ["aliteracy", "books", "classic", "humor"]},
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "quote": "\u201cImperfection is beauty, madness is genius and it's better to be absolutely ridiculous than absolutely boring.\u201d", "author": "Marilyn Monroe", "tags": ["be-yourself", "inspirational"]},
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "quote": "\u201cTry not to become a man of success. Rather become a man of value.\u201d", "author": "Albert Einstein", "tags": ["adulthood", "success", "value"]},
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "quote": "\u201cIt is better to be hated for what you are than to be loved for what you are not.\u201d", "author": "Andr\u00e9 Gide", "tags": ["life", "love"]},
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "quote": "\u201cI have not failed. I've just found 10,000 ways that won't work.\u201d", "author": "Thomas A. Edison", "tags": ["edison", "failure", "inspirational", "paraphrased"]},
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "quote": "\u201cA woman is like a tea bag; you never know how strong it is until it's in hot water.\u201d", "author": "Eleanor Roosevelt", "tags": ["misattributed-eleanor-roosevelt"]},
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "quote": "\u201cA day without sunshine is like, you know, night.\u201d", "author": "Steve Martin", "tags": ["humor", "obvious", "simile"]},
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "author": "Albert Einstein", "quote": "\u201cThe world as we have created it is a process of our thinking. It cannot be changed without changing our thinking.\u201d", "tags": ["change", "deep-thoughts", "thinking", "world"], "author_born_date": "March 14, 1879", "author_born_location": "in Ulm, Germany", "author_description": "in Ulm, Germany"}
]

交给子目录yield

    def parse(self,response):
        for quote in response.css('div.quote'):
            item = QuotesItem()
            item['quote'] = quote.css('span.text::text').extract_first()
            item['author'] = quote.css('small.author::text').extract_first()
            item['tags'] = quote.css('div.tags a.tag::text').extract()
            author_page = response.css('small.author+a::attr(href)').extract_first()
            item['authro_full_url'] = response.urljoin(author_page)
            


            yield scrapy.Request(url=item['authro_full_url'], meta={'item':item},callback=self.parse_author)
            

    def parse_author(self,response):
        item = response.meta['item']
        item['author_born_date'] = response.css('.author-born-date::text').extract_first()
        item['author_born_location'] = response.css('.author-born-location::text').extract_first()
        item['author_description'] = response.css('.author-born-location::text').extract_first()        
        yield item

最后只有一个

[
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "author": "Albert Einstein", "quote": "\u201cThe world as we have created it is a process of our thinking. It cannot be changed without changing our thinking.\u201d", "tags": ["change", "deep-thoughts", "thinking", "world"], "author_born_date": "March 14, 1879", "author_born_location": "in Ulm, Germany", "author_description": "in Ulm, Germany"}
]

关闭Scrapy的去重机制

加上参数，不要过滤

    def parse(self,response):
        for quote in response.css('div.quote'):
            item = QuotesItem()
            item['quote'] = quote.css('span.text::text').extract_first()
            item['author'] = quote.css('small.author::text').extract_first()
            item['tags'] = quote.css('div.tags a.tag::text').extract()
            author_page = response.css('small.author+a::attr(href)').extract_first()
            item['authro_full_url'] = response.urljoin(author_page)
            


            yield scrapy.Request(url=item['authro_full_url'], meta={'item':item},callback=self.parse_author,dont_filter=True)
            

    def parse_author(self,response):
        item = response.meta['item']
        item['author_born_date'] = response.css('.author-born-date::text').extract_first()
        item['author_born_location'] = response.css('.author-born-location::text').extract_first()
        item['author_description'] = response.css('.author-born-location::text').extract_first()        
        yield item

最后结果json文件

[
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "author": "Albert Einstein", "quote": "\u201cTry not to become a man of success. Rather become a man of value.\u201d", "tags": ["adulthood", "success", "value"], "author_born_date": "March 14, 1879", "author_born_location": "in Ulm, Germany", "author_description": "in Ulm, Germany"},
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "author": "Marilyn Monroe", "quote": "\u201cImperfection is beauty, madness is genius and it's better to be absolutely ridiculous than absolutely boring.\u201d", "tags": ["be-yourself", "inspirational"], "author_born_date": "March 14, 1879", "author_born_location": "in Ulm, Germany", "author_description": "in Ulm, Germany"},
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "author": "Steve Martin", "quote": "\u201cA day without sunshine is like, you know, night.\u201d", "tags": ["humor", "obvious", "simile"], "author_born_date": "March 14, 1879", "author_born_location": "in Ulm, Germany", "author_description": "in Ulm, Germany"},
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "author": "Andr\u00e9 Gide", "quote": "\u201cIt is better to be hated for what you are than to be loved for what you are not.\u201d", "tags": ["life", "love"], "author_born_date": "March 14, 1879", "author_born_location": "in Ulm, Germany", "author_description": "in Ulm, Germany"},
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "author": "Albert Einstein", "quote": "\u201cThere are only two ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle.\u201d", "tags": ["inspirational", "life", "live", "miracle", "miracles"], "author_born_date": "March 14, 1879", "author_born_location": "in Ulm, Germany", "author_description": "in Ulm, Germany"},
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "author": "J.K. Rowling", "quote": "\u201cIt is our choices, Harry, that show what we truly are, far more than our abilities.\u201d", "tags": ["abilities", "choices"], "author_born_date": "March 14, 1879", "author_born_location": "in Ulm, Germany", "author_description": "in Ulm, Germany"},
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "author": "Jane Austen", "quote": "\u201cThe person, be it gentleman or lady, who has not pleasure in a good novel, must be intolerably stupid.\u201d", "tags": ["aliteracy", "books", "classic", "humor"], "author_born_date": "March 14, 1879", "author_born_location": "in Ulm, Germany", "author_description": "in Ulm, Germany"},
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "author": "Albert Einstein", "quote": "\u201cThe world as we have created it is a process of our thinking. It cannot be changed without changing our thinking.\u201d", "tags": ["change", "deep-thoughts", "thinking", "world"], "author_born_date": "March 14, 1879", "author_born_location": "in Ulm, Germany", "author_description": "in Ulm, Germany"},
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "author": "Thomas A. Edison", "quote": "\u201cI have not failed. I've just found 10,000 ways that won't work.\u201d", "tags": ["edison", "failure", "inspirational", "paraphrased"], "author_born_date": "March 14, 1879", "author_born_location": "in Ulm, Germany", "author_description": "in Ulm, Germany"},
{"authro_full_url": "http://quotes.toscrape.com/author/Albert-Einstein", "author": "Eleanor Roosevelt", "quote": "\u201cA woman is like a tea bag; you never know how strong it is until it's in hot water.\u201d", "tags": ["misattributed-eleanor-roosevelt"], "author_born_date": "March 14, 1879", "author_born_location": "in Ulm, Germany", "author_description": "in Ulm, Germany"}
]