我注册了一个事件来更新User.name，以便在更新之后或之前应用一些规则。
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
from sqlalchemy import event
from sqlalchemy import Column, Integer, String
from sqlalchemy.ext.declarative import declarative_base
engine = create_engine('sqlite:///:memory:', echo=True)
Session = sessionmaker(bind=engine) # engine part
Base = declarative_base()
class User(Base):
__tablename__ = 'users'
id = Column(Integer, primary_key=True)
name = Column(String)
fullname = Column(String)
password = Column(String)
rule = Column(String)
Base.metadata.create_all(engine)
session = Session()
u1 = User(id=1, name="hello world", fullname="hello kitty")
u2 = User(id=2, name="hello world2", fullname="hello kitty2")
session.add(u1)
session.add(u2)
@event.listens_for(User, 'before_update')
def User_before_update(target, value, initiator):
print ":::::received before insert event for target"
@event.listens_for(User.name, 'set')
def name_set(target, value, old_value, initiator):
print ":::::set before insert event for target"
### option A
user = session.query(User).get(2)
user.name = u"wawamsma"
session.merge(user)
### option B
session.query(User).filter(User.id == 2).update({User.name: u"eenimenee"})
选项A
所有内容都运行良好，但是我有一些使用许多字段对SQLAlchemy进行更新的方法。
选项B
已更新，但不会触发两个打印函数。
所以我想知道，这是注册事件的错误方式还是更新的错误方式？