使用Scrapy

Question

尝试抓取以下网页http://www.starcitygames.com/catalog/category/1009?&start=0，在大多数情况下，我会得到期望的值，但是有些值会返回空值，而且我不知道如何摆脱这些空值并获得那里的实际价值。

[

SplashSpider.py

import csv
from scrapy.spiders import Spider
from scrapy_splash import SplashRequest
from ..items import GameItem
def process_csv(csv_file):
    data = []
    reader = csv.reader(csv_file)
    next(reader)
    for fields in reader:
        if fields[0] != "":
            url = fields[0]
        else:
            continue # skip the whole row if the url column is empty
        if fields[1] != "":
            ip = "http://" + fields[1] + ":8050" # adding http and port because this is the needed scheme
        if fields[2] != "":
            useragent = fields[2]
        data.append({"url": url, "ip": ip, "ua": useragent})
    return data
class MySpider(Spider):
    name = 'splash_spider'  # Name of Spider

    # notice that we don't need to define start_urls
    # just make sure to get all the urls you want to scrape inside start_requests function

    # getting all the url + ip address + useragent pairs then request them
    def start_requests(self):

        # get the file path of the csv file that contains the pairs from the settings.py
        with open(self.settings["PROXY_CSV_FILE"], mode="r") as csv_file:
           # requests is a list of dictionaries like this -> {url: str, ua: str, ip: str}
            requests = process_csv(csv_file)

        for req in requests:
            # no need to create custom middlewares  # just pass useragent using the headers param, and pass proxy using the meta param

            yield SplashRequest(url=req["url"], callback=self.parse, args={"wait": 3},
                    headers={"User-Agent": req["ua"]},
                    splash_url = req["ip"],
                    )
 # Scraping
    def parse(self, response):
        item = GameItem()
        for game in response.css("tr"):
            # Card Name

            yield {
                    'card_name':  game.css("a.card_popup::text").get(),
                    'stock': game.css("td.deckdbbody.search_results_8::text").get(),
                    'price': game.css("td.deckdbbody.search_results_9::text").get()
                    }

items.py

进口沙皮

class GameItem(scrapy.Item):
    card_name  = scrapy.Field()
    stock = scrapy.Field()
    price = scrapy.Field()

Answer 1

首先，您只需要处理包含卡信息的行，而忽略其余所有行。接下来，您需要记住前几行（current_card_name）中的卡名：

def parse(self, response):
    # item = GameItem()
    current_card_name = ""
    for card_row in response.xpath(
            '//tr[starts-with(@class, "deckdbbody")]'):

        card_name = card_row.xpath(
            './/a[@class="card_popup"]/text()').extract_first()
        if not card_name:
            card_name = current_card_name
        else:
            current_card_name = card_name

        stock = card_row.xpath(
            './/td[contains(@class, "search_results_8")]/text()').extract_first()
        price = card_row.xpath(
            './/td[contains(@class, "search_results_9")]/text()').extract_first()

        yield {
            'card_name': card_name,
            'stock': stock,
            'price': price
        }