weak_reference_model.py

class User(DeclarativeBase):
    __tablename__ = 'sys_user'

    user_id = Column(Integer, autoincrement=True, primary_key=True)
    email = Column(Unicode(100))
    name = Column(Unicode(100))

class UserLog(DeclarativeBase):
    __tablename__ = 'sys_user_log'

    log_id = Column(Integer, autoincrement=True, primary_key=True)
    log_type = Column(Unicode(10), nullable=False)
    user_id = Column(Integer, nullable=False, index=True)
    user = relation('User',
                    foreign_keys=[user_id],
                    primaryjoin='UserLog.user_id == foreign(User.user_id)',
                    backref=backref('logs'))