步骤1：定义数据结构（items.py） 

import scrapy
class GlobalProductItem(scrapy.Item):
 # 基础信息
 name = scrapy.Field()
 sku = scrapy.Field()
 price = scrapy.Field()
 currency = scrapy.Field()
 source_site = scrapy.Field()
 
 # 时间戳
 crawl_time = scrapy.Field()
 
 # 处理后字段
 normalized_price = scrapy.Field(
 serializer=lambda x: f"${x:.2f}" # 序列化处理
 )
 
 # 位置信息
 ship_from_country = scrapy.Field()
 ship_to_countries = scrapy.Field()
 
 # 分类维度
 category = scrapy.Field()
 subcategory = scrapy.Field()
# 标记字段
 discount_tag = scrapy.Field()
 is_out_of_stock = scrapy.Field()
 
 # 详情⻚元数据
 product_url = scrapy.Field()
 image_urls = scrapy.Field()