使用"select“作为关联表的sqlalchemy自引用多对多

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

Base = declarative_base()

association_table = Table('association', Base.metadata,
    Column('left_id', Integer, ForeignKey('entity.id')),
    Column('right_id', Integer, ForeignKey('entity.id'))
)

class Entity(Base):
    __tablename__ = 'entity'
    id = Column(Integer, primary_key=True)
    name = Column(String)
    children = relationship('Entity',
                            secondary=association_table,
                            primaryjoin=id==association_table.c.left_id,
                            secondaryjoin=id==association_table.c.right_id,
                            backref='parents')

engine = create_engine('数据库连接字符串')

Base.metadata.create_all(engine)