Hi everyone, 
I am searching but I find no solution for my issue that is why I decided to 
ask here. Thanks in advance for your attention. 

The issue is related to the update of a second level hierarchy object Id. I 
am creating a hierarchy, following the recommendations in the tutorials but 
I find that when I want to update the id, which is the link between all the 
entities through the foreign key, only the first and the third level (last 
level) of the hierarchy update the id value. I think this could be an issue 
because the id is what will link the tables for further queries. I attach 
an example of the code:

from sqlalchemy import (
   Column, Integer, String, create_engine,
   ForeignKey)
from sqlalchemy.orm import create_session
from sqlalchemy.ext.declarative import declarative_base

e = create_engine("sqlite:///test.db", echo=True)
Base = declarative_base(bind=e)


class Employee(Base):
   __tablename__ = 'employees'

    employee_id = Column(Integer, primary_key=True)
   name = Column(String(50))
   type = Column(String(30), nullable=False)

    __mapper_args__ = {
       'polymorphic_identity': 'employee',
       'polymorphic_on': type,
       'with_polymorphic': '*'
       }

    def __init__(self, name):
       self.name = name


class Manager(Employee):
   __tablename__ = 'managers'
   __mapper_args__ = {'polymorphic_identity': 'manager'}

    employee_id = Column(
       Integer,
       ForeignKey('employees.employee_id'),
       primary_key=True
   )
   manager_data = Column(String(50))

    def __init__(self, name, manager_data):
       super(Manager, self).__init__(name)
       self.manager_data = manager_data


class Owner(Manager):
   __tablename__ = 'owners'
   __mapper_args__ = {'polymorphic_identity': 'owner'}

    employee_id = Column(
       Integer,
       ForeignKey('employees.employee_id'),
       ForeignKey('managers.employee_id'),
       primary_key=True
   )
   owner_secret = Column(String(50))

    def __init__(self, name, manager_data, owner_secret):
       super(Owner, self).__init__(name, manager_data)
       self.owner_secret = owner_secret


Base.metadata.drop_all()
Base.metadata.create_all()

s = create_session(bind=e, autoflush=True, autocommit=False)    
o = Owner('nosklo', 'mgr001', 'ownerpwd')
s.add(o)
s.commit()

el = s.query(Owner).one()
# for el in session.query(Product, Event,Travel).all():
print(el)
el.employee_id = 33
# el.manager_data='hello'
s.commit()


The response when running this is :
2019-06-12 16:07:36,232 INFO sqlalchemy.engine.base.Engine UPDATE employees 
SET employee_id=? WHERE employees.employee_id = ?
2019-06-12 16:07:36,233 INFO sqlalchemy.engine.base.Engine (33, 1)
2019-06-12 16:07:36,233 INFO sqlalchemy.engine.base.Engine UPDATE owners 
SET employee_id=? WHERE owners.employee_id = ?
2019-06-12 16:07:36,233 INFO sqlalchemy.engine.base.Engine (33, 1)
2019-06-12 16:07:36,234 INFO sqlalchemy.engine.base.Engine COMMIT

So it is not updating my Manager table....and that is a big issue....
Any idea about it?

Thanks

-- 
SQLAlchemy - 
The Python SQL Toolkit and Object Relational Mapper

http://www.sqlalchemy.org/

To post example code, please provide an MCVE: Minimal, Complete, and Verifiable 
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