from sqlalchemy import create_engine, MetaData, Table
from sqlalchemy.orm import mapper
from sqlalchemy.sql import select

from config import settings


class Persona(object):
    pass


engine = create_engine(settings.database_url)
metadata = MetaData(engine)

tabla_persona = Table('tb_personas', metadata, autoload=True)
mapper(Persona, tabla_persona)

print(tabla_persona.columns)

# Ejecutar una query
conn = engine.connect()
s = select([Persona.Apellido]).where(Persona.id == 802)
res = conn.execute(s)
row = res.fetchone()
res = None if row is None else row['ColumnName']
print(res)