灯塔急切加载关系

from sqlalchemy import create_engine, Column, Integer, String, ForeignKey
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker, relationship

Base = declarative_base()

class User(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True)
    name = Column(String)
    orders = relationship('Order', back_populates='user', lazy='joined')  # 急切加载

class Order(Base):
    __tablename__ = 'orders'
    id = Column(Integer, primary_key=True)
    user_id = Column(Integer, ForeignKey('users.id'))
    user = relationship('User', back_populates='orders')

engine = create_engine('sqlite:///example.db')
Base.metadata.create_all(engine)
Session = sessionmaker(bind=engine)
session = Session()

# 查询用户及其订单（急切加载）
user = session.query(User).options(joinedload(User.orders)).filter_by(id=1).first()
print(user.name)
for order in user.orders:
    print(order.id)