Python 从SQLAlchemy中的M:N关系获取所有值

我将sqlalchemy中的M:N关系定义为：

association_table = Table('association_table', base.metadata,
                          Column('content_id', UUID(as_uuid=True),
                                 ForeignKey('content.content.content_id'), primary_key=True),
                          Column('message_id', UUID(as_uuid=True), ForeignKey('messages.webhooks.message_id'), primary_key=True),
                          schema='content'
                          )
class Messsages(base):
    __table_args__ = {"schema": "messages"}
    __tablename__ = 'webhooks'
    id = Column('message_id', UUID(as_uuid=True), primary_key=True)
    parents = relationship(
        "Content",
        secondary=association_table,
        back_populates="children", uselist=False)

class Content(base):
    __tablename__ = "content"
    __table_args__ = {"schema": "content"}
    id = Column("content_id", UUID(as_uuid=True), primary_key=True)
    children = relationship(
        Messsages,
        secondary=association_table,
        uselist=False,
        back_populates="parents")


class ContentRepository:
    def __init__(self, session):

    def get_all(self):
        return self.session.query(Content).all()


for config in ContentRepository(session).get_all():
        ids = config.children.id

我在ids中只得到一个值，表中有多行，但它只返回一个值