Hi,
I am actually using both MySQL and SQLite (one on the dev machine, one
on the server).
Does that make a difference?
On Jul 27, 12:26 pm, Michael Bayer <mike...@zzzcomputing.com> wrote:
> On Jul 25, 2011, at 9:47 AM, Aviv Giladi wrote:
>
>
>
>
>
>
>
>
>
> > I can't seem to make cascade deletes work in sqlalchemy.
>
> > I have a parent class (called Rating), a sub class (Subrating) and a
> > third class called SubRatingProperty.
>
> > There is a one-to-one relationship between Rating and SubRating - each
> > Rating can only have one specific SubRating object. Next, the
> > SubRatingProperty refers to a row in a table with fixed values. There
> > are 3 SubRatingProperty entries - property1, property2 and property3.
> > The SubRating class can have one or more of either property1,
> > property2 and property3, therefore the relationship is many-to-many (a
> > SubRatingProperty can have more than one properties, and for example
> > property1 can be assigned to more than one SubRatingProperty's).
>
> > Here is the code that defines all of this:
>
> > subrating_subratingproperty_association =
> > Table('subrating_subratingproperty_association', Base.metadata,
> > Column('subrating_id', Integer,
> > ForeignKey('subratings.id')),
> > Column('subrating_property_id',
> > Integer, ForeignKey('subrating_properties.id')))
>
> > class SubRatingProperty(Base):
> > __tablename__ = 'subrating_properties'
> > id = Column(Integer, primary_key=True)
> > name = Column(Unicode(32), unique=True)
> > subratings = relationship("SubRating",
>
> > secondary=subrating_subratingproperty_association,
> > backref="subrating_properties")
>
> > class SubRating(Base):
> > __tablename__ = 'subratings'
> > id = Column(Integer, primary_key=True)
> > name = Column(Unicode(32), unique=True)
>
> > class Rating(Base):
> > __tablename__ = 'ratings'
> > id = Column(Integer, primary_key=True)
> > name = Column(Unicode(32), unique=True)
> > subrating_id = Column(Integer, ForeignKey('subratings.id'))
> > subrating = relationship("SubRating", backref=backref("rating",
> > uselist=False))
> > Everything works fine, but I can't figure out how to do cascade
> > deletes. I am deleting Rating objects, and when I do, I would like the
> > according SubRating object to be deleted, as well as all the entries
> > in the association table. So deleting Rating1 would delete its
> > SubRating, as well as all the connection between the SubRating and
> > SubRatingProperty's.
>
> > I have tried adding cascade="all" to the relationship call,
>
> you have two relationships() here to build the full chain so you'd need
> "cascade='all, delete-orphan'" on both Rating.subrating as well as
> SubRating.subrating_properties (use the backref() function instead of a
> string to establish the cascade rule on that end.
>
> > and I also
> > tried adding ondelete="cascade") to the ForeignKey call.
>
> if all the involved FOREIGN KEYs are generated with ON DELETE CASCADE as this
> would accomplish, as long as you are not on SQLIte or MySQL MyISAM the
> deletes will be unconditional.
--
You received this message because you are subscribed to the Google Groups
"sqlalchemy" group.
To post to this group, send email to sqlalchemy@googlegroups.com.
To unsubscribe from this group, send email to
sqlalchemy+unsubscr...@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/sqlalchemy?hl=en.
