在包含3个表的数据库中使用SQLAlchemy创建嵌套连接

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

Base = declarative_base()

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

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

class Product(Base):
    __tablename__ = 'products'
    id = Column(Integer, primary_key=True)
    name = Column(String)
    order_id = Column(Integer, ForeignKey('orders.id'))
    order = relationship('Order', back_populates='products')

from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker

# 创建数据库引擎
engine = create_engine('数据库连接字符串')

# 创建Session
Session = sessionmaker(bind=engine)
session = Session()

# 查询用户的订单及订单中的产品信息
users = session.query(User).all()
for user in users:
    print(f'用户：{user.name}')
    for order in user.orders:
        print(f'订单：{order.id}')
        for product in order.products:
            print(f'产品：{product.name}')