Python sqlalchemy -保存一对多的多个对象

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

Base = declarative_base()

class Author(Base):
    __tablename__ = 'authors'
    id = Column(Integer, primary_key=True)
    name = Column(String)
    books = relationship("Book", back_populates="author")

class Book(Base):
    __tablename__ = 'books'
    id = Column(Integer, primary_key=True)
    title = Column(String)
    author_id = Column(Integer, ForeignKey('authors.id'))
    author = relationship("Author", back_populates="books")

from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker

engine = create_engine('sqlite:///library.db')
Base.metadata.create_all(engine)

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

author1 = Author(name='John Smith')
book1 = Book(title='Python Basics')
book2 = Book(title='Advanced Python')
author1.books = [book1, book2]

session.add(author1)
session.commit()