管道文件存在问题，因为它未获取书名。而是为每次抓取保存一张 None.jpg 的随机图像

Question

items.py 文件。因为我知道 image_urls 和图像字段。它没有造成任何问题。

import scrapy
from scrapy.loader.processors import TakeFirst

class BooksToScrapeItem(scrapy.Item):
    image_urls = scrapy.Field()
    images = scrapy.Field()
    book_name = scrapy.Field(
        output_processor = TakeFirst()
    )

pipelines.py 文件。我认为 get_media_request 方法一定有问题，因为它没有从项目文件

中获取 book_name

from scrapy.pipelines.images import ImagesPipeline
from scrapy import Request


class BooksToScrapeImagePipeline(ImagesPipeline):

    def get_media_requests(self, item, info):
        return [Request(x,meta={'bookname': item.get('book_name')}) for x in item.get(self.images_urls_field, [])] #i think that the problem is in this line

    def file_path(self, request, response=None, info=None):

        return 'full/%s.jpg' % (request.meta['bookname'])

我为 scraping.It 使用的蜘蛛文件在我没有自定义管道文件时工作。

import scrapy
from scrapy.loader import ItemLoader
from books_to_scrape.items import BooksToScrapeItem

class ImgscrapeSpider(scrapy.Spider):
    name = 'imgscrape'
    allowed_domains = ['books.toscrape.com']
    start_urls = ['http://books.toscrape.com']

    def parse(self, response):
        for article in response.xpath("//article[@class='product_pod']"):
            loader = ItemLoader(item=BooksToScrapeItem(),selector=article)
            relative_url = article.xpath(".//div/a/img[@class='thumbnail']/@src").extract_first()
            abs_url = response.urljoin(relative_url)
            loader.add_value('image_urls',abs_url)
            loader.add_xpath('book_name',".//article[@class='product_pod']/h3/a/text()") 
            yield loader.load_item()

Answer 1

你的问题出在相对 xpath 中

loader.add_xpath('book_name', ".//article[@class='product_pod']/h3/a/text()")

加载程序使用 xpath("//article[@class='product_pod']") 作为选择器

   for article in response.xpath("//article[@class='product_pod']"):
        loader = ItemLoader(item=BooksToScrapeItem(), selector=article)

所以所有的相对 xpath 都是相对于 "//article[@class='product_pod']" 并且它们在 xpath 中不需要 "//article[@class='product_pod']"。

使用相对 xpath ".//article[@class='product_pod']/h3/a/text()" 找不到标题，因此 book_name 对于所有项目都是空的，对于所有使用 None 作为标题的项目 - 并且它使用相同的名称None.jpg 所有图像。

必须

loader.add_xpath('book_name', ".//h3/a/text()")  # title with `...`

顺便说一句： text() 没有完整的标题，但有 ...。要获得完整的标题，您必须获得属性 title=

loader.add_xpath('book_name', ".//h3/a/@title")  # full title

我在一个文件中创建了所有代码的版本运行它没有创建项目。

每个人都可以将它复制到单个文件并运行测试它。

import scrapy
from scrapy.loader.processors import TakeFirst

class BooksToScrapeItem(scrapy.Item):
    image_urls = scrapy.Field()
    images = scrapy.Field()
    book_name = scrapy.Field(
        output_processor = TakeFirst()
    )

from scrapy import Request
from scrapy.pipelines.images import ImagesPipeline

class BooksToScrapeImagePipeline(ImagesPipeline):

    def get_media_requests(self, item, info):
        return [Request(x, meta={'bookname': item.get('book_name')}) for x in item.get(self.images_urls_field, [])] #i think that the problem is in this line

    def file_path(self, request, response=None, info=None):
        return 'full/%s.jpg' % request.meta['bookname']

from scrapy.loader import ItemLoader

class ImgscrapeSpider(scrapy.Spider):
    name = 'imgscrape'
    allowed_domains = ['books.toscrape.com']
    start_urls = ['http://books.toscrape.com']

    def parse(self, response):
        for article in response.xpath("//article[@class='product_pod']"):

            loader = ItemLoader(item=BooksToScrapeItem(),selector=article)

            relative_url = article.xpath(".//div/a/img[@class='thumbnail']/@src").extract_first()
            abs_url = response.urljoin(relative_url)

            loader.add_value('image_urls', abs_url)
            #loader.add_xpath('book_name',".//article[@class='product_pod']/h3/a/text()")  # wrong relative xpath 
            #loader.add_xpath('book_name', ".//h3/a/text()")  # only partial title
            loader.add_xpath('book_name', ".//h3/a/@title")  # full title

            yield loader.load_item() 

# -----------------------------------------------------------------------------

from scrapy.crawler import CrawlerProcess

c = CrawlerProcess({
    'USER_AGENT': 'Mozilla/5.0',

    # save in file CSV, JSON or XML
    'FEED_FORMAT': 'csv',     # csv, json, xml
    'FEED_URI': 'output.csv', #

    # download images to `IMAGES_STORE/full` (standard folder) and convert to JPG (even if it is already JPG)
    # it needs `yield {'image_urls': [url]}` in `parse()` and both ITEM_PIPELINES and IMAGES_STORE to work

    'ITEM_PIPELINES': {'__main__.BooksToScrapeImagePipeline': 1},            # used Pipeline create in current file (needs __main___)
    'IMAGES_STORE': '.',                   # this folder has to exist before downloading

})
c.crawl(ImgscrapeSpider)
c.start()

管道文件存在问题，因为它未获取书名。而是为每次抓取保存一张 None.jpg 的随机图像

There is a problem in pipelines file as it is not fetching the book name. instead saving one random image with None.jpg for each crawl

python

filenames

scrapy