如何将父对象的id推送到子对象？

CREATE TABLE orders (
    order_id INT PRIMARY KEY,
    customer_name VARCHAR(255)
);

CREATE TABLE order_items (
    item_id INT PRIMARY KEY,
    order_id INT,
    product_name VARCHAR(255),
    FOREIGN KEY (order_id) REFERENCES orders(order_id)
);

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

Base = declarative_base()

class Order(Base):
    __tablename__ = 'orders'
    order_id = Column(Integer, primary_key=True)
    customer_name = Column(String)
    items = relationship("OrderItem", back_populates="order")

class OrderItem(Base):
    __tablename__ = 'order_items'
    item_id = Column(Integer, primary_key=True)
    order_id = Column(Integer, ForeignKey('orders.order_id'))
    product_name = Column(String)
    order = relationship("Order", back_populates="items")

# 创建数据库连接
engine = create_engine('sqlite:///example.db')
Base.metadata.create_all(engine)

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

# 创建订单和订单项
new_order = Order(customer_name="John Doe")
new_item1 = OrderItem(product_name="Laptop")
new_item2 = OrderItem(product_name="Smartphone")

# 关联订单和订单项
new_order.items.append(new_item1)
new_order.items.append(new_item2)

# 添加到数据库
session.add(new_order)
session.commit()

# 查询验证
order = session.query(Order).filter_by(customer_name="John Doe").first()
for item in order.items:
    print(f"Order ID: {item.order_id}, Product: {item.product_name}")