教练，我想更骚 ：sqlalchemy，含有类成员不想存入数据库

问题 ：AttributeError: 'SPU' object has no attribute 'events'

orm

from sqlalchemy import MetaData, Table, String
from sqlalchemy.orm import mapper
import model

metadata = MetaData()

spu = Table(
    'spu', metadata,
    Column('name', String(255), primary_key=True),
    Column('title', String(255)),
    Column('pictures', String(1023)),
    Column('details', String(1023)),
    Column('is_sale', Boolean),
)

mapper(model.SPU, spu)

model

class SPU:

    def __init__(self, name, title, details, pictures):
        self.name = name
        self.title = title
        self.details = details
        self.pictures = pictures
        self.is_sale = False
        self.events = []

可以看到，在sqlalchemy的Table里面并没有events字段

原因：存在成员但不存入数据库的时候需要监听事件再添加

改正后的orm代码

from sqlalchemy import MetaData, Table, String, event
from sqlalchemy.orm import mapper
import model

metadata = MetaData()

spu = Table(
    'spu', metadata,
    Column('name', String(255), primary_key=True),
    Column('title', String(255)),
    Column('pictures', String(1023)),
    Column('details', String(1023)),
    Column('is_sale', Boolean),
)

mapper(model.SPU, spu)

@event.listens_for(model.SPU, 'load')
def receive_spu_load(spu, _)
    spu.events = []