Bdtjtk

I am very confused and I am trying to add children to an existing parent object in the database. When trying to do that I get an error.

I am unsure about how to make sure my newly added children object gets saved?
The error and my attempts are below:

equityLinkedNote = db.session.query(EquityLinkedNote).filter(EquityLinkedNote.cmdb == cmdb_eln.cmdb)

underlier_list = underliers.to_dict(orient="records")

    equityLinkedNote.Underlier =

                [UnderlierDetails(

                Ticker=underlier["Ticker"] if "Ticker" in underlier else None,

                Weight=underlier["Weight"] if "Weight" in underlier else None,

                ReturnFloor=underlier["ReturnFloor"] if "ReturnFloor" in underlier else None,

                InitialFixing=underlier["InitialFixing"] if "InitialFixing" in underlier else None,

                ReturnCap=underlier["ReturnCap"] if "ReturnCap" in underlier else None,

                EffectiveDate=underlier["EffectiveDate"] if "EffectiveDate" in underlier else cmdb_eln.trade_date

                ) for underlier in underlier_list]

    db.session.flush()

    db.session.commit()

ERROR

File "....libsite-packagessqlalchemyextdeclarativebase.py", line 747, in _declarative_constructor

    setattr(self, k, kwargs[k])

  File "...site-packagessqlalchemyormattributes.py", line 229, in __set__

    instance_dict(instance), value, None)

  File "...site-packagessqlalchemyormattributes.py", line 711, in set

    state._modified_event(dict_, self, old)

AttributeError: 'NoneType' object has no attribute '_modified_event'

I have no idea why this is failing. any help will be appreciated!

Here are my models

class EquityLinkedNote(GenericSecMasterObject):

    Underlier = db.relationship("UnderlierDetails", backref='note', cascade="save-update, merge, delete", lazy='dynamic',

                                collection_class=list)

Underlier

class UnderlierDetails(db.Model):

    __tablename__ = "underlier_details"

    id = db.Column(db.Integer, primary_key=True)

    Ticker = db.Column(db.String(50), nullable=False)

    InitialFixing = db.Column(db.Float, nullable=True)  

    ReturnCap = db.Column(db.Float, nullable=True)  

    ReturnFloor = db.Column(db.Float, nullable=True)  

    Weight = db.Column(db.Float, nullable=True)

    EffectiveDate = db.Column(db.DateTime, nullable=False)

    cmdb = db.Column(db.String(20), db.ForeignKey('sec_master_details.cmdb'), nullable=False)

I realized my error, for anyone who has similair issue, refrain from using the following in a db.Model, removed it and the error was resolved...

def __getattr__(self, item):

    return None