Scrapy项目错误:“未定义变量”,实际上我已经定义了这个变量

https://www.practicalecommerce.com/Monitor-Competitor-Prices-with-Python-and-Scrapy 具体是怎么说的,一步一步,但当我用命令运行爬行器时:

瘙痒爬行质量效应-o结果。csv

它显示了这个错误:

NameError:未定义全局名称“TfawItem”

我做错了什么?

这是我的物品。py:

# -*- coding: utf-8 -*-

# Define here the models for your scraped items
#
# See documentation in:
# http://doc.scrapy.org/en/latest/topics/items.html

import scrapy


class TfawItem(scrapy.Item):
    # define the fields for your item here like:
    # name = scrapy.Field()
    title = scrapy.Field()
    price = scrapy.Field()
    upc = scrapy.Field()
    url = scrapy.Field()

我的质量效应。py:

# -*- coding: utf-8 -*-
import scrapy


class MasseffectSpider(scrapy.Spider):
    name = 'massEffect'
    allowed_domains = ['tfaw.com']
    start_urls = [
        'http://www.tfaw.com/Companies/Dark-Horse/Series?series_name=Mass+Effect',
    ]

    def parse(self, response):
        for href in response.css('div a.boldlink::attr(href)'):
            url = response.urljoin(href.extract())
            yield scrapy.Request(url, callback=self.parse_detail_page)

    def parse_detail_page(self, response):
        comic = TfawItem()
        comic['title'] = response.css('div.iconistan + b span.blackheader::text').extract()
        comic['price'] = response.css('span.blackheader ~ span.redheader::text').re('[$]\d+\.\d+')
        comic['upc'] = response.xpath('/html/body/table[1]/tr/td[4]/table[3]/tr/td/table/tr/td[contains(., "UPC:")]/following-sibling::td[1]/text()').extract()
        comic['url'] = response.url
        yield comic

以及我项目的层次结构:

tfaw/

    scrapy.cfg

    results.csv

    tfaw/

        __init__.py

        __init__.pyc

        items.py

        middlewares.py

        pipelines.py

        settings.py

        settings.pyc

        spiders/

            __init__.py

            __init__.pyc

            massEffect.py

            massEffect.pyc