you would need to illustrate an MCVE of what's happening. objects
don't "lose track" of their related objects unless yes, you deleted
them, in which case you should not expect that they would be there.
when the object is expired, it will go to reload them, and they'll be
gone.
On Tue, Aug 22, 2017 at 11:05 AM, cecemel <ruiz.felixr...@gmail.com> wrote:
> @update:
>
> calling the flush doen't seem to make any difference. At some point, the
> object looses track of it's grandparents
>
>
> On Tuesday, August 22, 2017 at 3:57:23 PM UTC+2, cecemel wrote:
>>
>> Hi,
>>
>> so, I'm currently facing this issue, where I would like to do some calls
>> to an external service, when my object has been deleted within a flush.
>> For this operation to occur, I need the id from my model object, but also
>> the id from the parent of the parent object model. There are cases, where I
>> am unable to access them (I guess, depending of the order of the execution)
>> and I am unsure on what to do next.
>>
>> So if you're willing to give me some advice, would be awesome.
>>
>> Here is a dummy model:
>>
>> from sqlalchemy import event
>>
>> from sqlalchemy import *
>> from sqlalchemy.ext.declarative import declarative_base
>> from sqlalchemy.orm import sessionmaker, backref, relationship
>>
>> Base = declarative_base()
>>
>>
>>
>> #########################################################################################
>> # MODEL
>>
>> #########################################################################################
>> class House(Base):
>> __tablename__ = 'house'
>> id = Column(Integer, primary_key=True)
>> rooms = relationship("Room",
>> backref=backref("house", lazy="joined"),
>> cascade='all, delete-orphan')
>>
>>
>> class Room(Base):
>> __tablename__ = 'room'
>> id = Column(Integer, primary_key=True)
>> house_id = Column(Integer, ForeignKey('house.id'))
>> beds = relationship("Bed",
>> backref=backref("room", lazy="joined"),
>> cascade='all, delete-orphan')
>>
>>
>> class Bed(Base):
>> __tablename__ = 'bed'
>> id = Column(Integer, primary_key=True)
>> room_id = Column(Integer, ForeignKey('room.id'))
>>
>>
>>
>> #########################################################################################
>> # CONFIG
>>
>> #########################################################################################
>> def setup():
>> engine = create_engine("sqlite:///foo.db", echo=True)
>>
>> Base.metadata.bind = engine
>> Base.metadata.create_all(engine)
>>
>> SessionFactory = sessionmaker(
>> bind=engine
>> )
>>
>> event.listen(SessionFactory, 'deleted_to_detached',
>> listener_bed_has_been_removed)
>>
>> return SessionFactory
>>
>>
>> def listener_bed_has_been_removed(session, instance):
>> if type(instance) is not Bed:
>> return
>>
>> bed_id = instance.id
>> house_id = instance.room.house.id # this is NOT ALWAYS there.
>> Depending on the order of the execution I guess
>>
>> print("execute the service call to external service here bed_id {},
>> house_id {}".format(bed_id, house_id))
>>
>>
>>
>>
>> So my question(s):
>>
>> Is there a clean way to always acces this parent's parent attribute?
>>
>> If not, would be starting a new session and query it from the event
>> handler be an option? (is it not dangerous, because it seems to work)
>>
>> Additional quirk, I am working within a transaction manager (pyramid_tm)
>> and ZopeTransactionExtension()
>>
>> Thanks!
>>
>>
>> More information about the system:
>>
>> SQLAlchemy 1.1.13
>>
>> Python 3.5
>>
>> Postgres 9.6
>
> --
> 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 Example. See http://stackoverflow.com/help/mcve for a full
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--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
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