class SampleMixin(object):
    id = Column('Id', Integer, primary_key=True)
name = Column('Name', String)
description = Column('Description', String)
is_active = Column('IsActive', Boolean)


class Sample(SampleMixin, Base):
    __tablename__ = 'Sample'
__table_args__ = {'useexisting': True}

def __init__(self, id, name, description, is_active):
    self.id = id
self.name = name
How to define metaclass for a class that extends from sqlalchemy declarative base