sqlalchemy.exc.ArgumentError: Mapper mapped class could not assemble any primary key columns for mapped

问题：sqlalchemy.exc.ArgumentError: Mapper mapped class UserTotal->user_total could not assemble any primary key columns for mapped

解决：sqlalchemy的model不能没有primary_key

方法：

class UserTotal(Base):
    __tablename__ = "user_total"

    dt = Column(Date, nullable=False)
    recent_days = Column(Integer, nullable=False)
    login_num_count = Column(BigInteger)
    page_count = Column(BigInteger)

    __mapper_args__ = { 
        'primary_key': [dt, recent_days]
    }