sqlalchemy中的多对多关系在添加和删除项时不会加载

# 定义多对多关系
association_table = Table('association', Base.metadata,
    Column('left_id', Integer, ForeignKey('left_table.id')),
    Column('right_id', Integer, ForeignKey('right_table.id'))
)

class LeftTable(Base):
    __tablename__ = 'left_table'
    id = Column(Integer, primary_key=True)
    rights = relationship("RightTable", secondary=association_table, back_populates="lefts")

class RightTable(Base):
    __tablename__ = 'right_table'
    id = Column(Integer, primary_key=True)
    lefts = relationship("LeftTable", secondary=association_table, back_populates="rights")

# 创建左表和右表的实例对象
left = LeftTable()
right = RightTable()

# 将右表的实例对象添加到多对多关系中
left.rights.append(right)

# 创建左表和右表的实例对象
left = LeftTable()
right = RightTable()

# 从多对多关系中删除项
left.rights.remove(right)