On Oct 18, 8:01 pm, Michael Bayer <mike...@zzzcomputing.com> wrote:
> On Oct 18, 2011, at 10:03 AM, fribes wrote:
>
>
>
> > Hi all,
>
> > Despite some doc and web digging, I didn't find how to tell sqa to behave
> > the way I want :
> > on deletion on Peripheral, also delete in Actuator.
>
> > with the following code, the record in Actuator remains after a deletion,
> > and a subsequent creation fails with IntegrityError.
>
> > class Peripheral(Base):
> > __tablename__ = 'peripheral'
> > id = Column(Integer, primary_key=True)
> > label = Column(String(20), nullable=False)
>
> > __mapper_args__ = {'polymorphic_on': peripheral_type,
> > 'polymorphic_identity': 'peripheral'}
>
> > class Actuator(Peripheral):
> > __tablename__ = 'actuator'
> > __mapper_args__ = {'polymorphic_identity': 'actuator'}
> > id = Column(None, ForeignKey('peripheral.id'), primary_key=True)
>
> > duration = Column(Integer)
>
> > Any suggestion ?
>
> usually relationship() with cascade="all, delete-orphan" is used for this use
> case, so that SQLAlchemy can maintain knowledge about the link between
> Peripheral and Actuator. The other alternative is to use "ON DELETE CASCADE"
> on the foreign key; this is part of the schema you'd generate in the database.
>
> Relevant docs:
>
> http://www.sqlalchemy.org/docs/orm/tutorial.html#configuring-delete-d...http://www.sqlalchemy.org/docs/core/schema.html#on-update-and-on-deletehttp://www.sqlalchemy.org/docs/orm/collections.html#using-passive-del...
>
>
>
> > Regards,
I forgot to mention I'm using SQLite, so ondelete="CASCADE" is not a
option.
Mike's suggestion is OK so far, I'll stick to it.
Thanks and best regards.
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