Items

就相当于mvc中的model

声名item

import scrapy

class Product(scrapy.Item):
    name = scrapy.Field()
    price = scrapy.Field()
    stock = scrapy.Field()
    last_updated = scrapy.Field(serializer=str)

创建item

product = Product(name='Desktop PC', price=1000)

获得item的field

 product['name']
 product.get('name')
 product['last_updated']
 product.get('last_updated', 'not set')

设置item的field的值

product['last_updated'] = 'today'

product['lala'] = 'test' # setting unknown field
Traceback (most recent call last):
    ...
KeyError: 'Product does not support field: lala'

获得所有的值

>>> product.keys()
['price', 'name']

>>> product.items()
[('price', 1000), ('name', 'Desktop PC')]

扩展

直接集成别的item就好了

class DiscountedProduct(Product):
    discount_percent = scrapy.Field(serializer=str)
    discount_expiration_date = scrapy.Field()

class SpecificProduct(Product):
    name = scrapy.Field(Product.fields['name'], serializer=my_serializer)

其他操作

复制items

product2 = Product(product)
product3 = product2.copy()

items转item

dict(product)

从dict创建item

Product({'name': 'Laptop PC', 'price': 1500})