It's not a self-referring relation : Child and Parent objects are
different types and tables. So "remote_side" won't help here I fear.
And I can't really specify the foreign key on the column in my special
case (that's what I do usually of course)
In a single inheritance pattern :
- my top level class (the one that creates the table) has no foreign
key at all, but has a 'id_foreign' column, used by its subclasses to
have relation with any types of mapped objects
- any subclass may have its own relation with a lambda object : that's
why I use foreign_keys and primaryjoin.
The above code is just a simple code that reproduce what happen in my
complex situation...
Maybe it is a silly idea to do that, and I should use multi-table
inheritance instead...
On 31 oct, 01:01, Michael Bayer <[EMAIL PROTECTED]> wrote:
> the many-to-one side of a self-referring relation() needs the
> "remote_side" argument to be set; in this case it would be on the
> relation(Parent, remote_side=Parent.id).
>
> Also if you specify a ForeignKey() on your Child.parent_id Column
> object, you won't need the "primaryjoin" or "foreign_keys" argument in
> either the relation() or the backef(). This is SQLA's more typical
> configurational style.
>
> On Oct 30, 2008, at 6:58 PM, GustaV wrote:
>
>
>
> > Hi everybody.
>
> > I'm stuck in something bad:
> > I use a relation with a arbitrary foreign key + backref (the reason is
> > that I use single table inheritance, and the relation happen only on
> > one of the subclasses, so I can't set the foreign key on the
> > table...). But I get quickly a circular dependency!
>
> > I don't really get why, so I wrote a piece of code to reproduce it and
> > post it here!
> > I hope someone got an explanation/solution! :)
>
> > Cheers!
> > ps: using the latest revision.
> > pps : I put the relation on the child side, but the same happens when
> > on the parent side.
>
> > from zope.sqlalchemy import ZopeTransactionExtension
> > from sqlalchemy.orm import scoped_session, sessionmaker, eagerload
> > from sqlalchemy import MetaData
> > from sqlalchemy.orm.interfaces import SessionExtension
> > from sqlalchemy.ext.declarative import declarative_base
> > from sqlalchemy import Table, Column, types
> > from sqlalchemy import ForeignKey, UniqueConstraint
> > from sqlalchemy.orm import relation, backref, synonym
> > from sqlalchemy import select, func
>
> > maker = sessionmaker(autoflush=True, autocommit=False,
> > extension=[ZopeTransactionExtension()])
> > DBSession = scoped_session(maker)
> > DeclarativeBase = declarative_base()
>
> > class Parent(DeclarativeBase):
> > __tablename__ = 'parent'
> > id = Column('id', types.Integer, primary_key=True,
> > nullable=False)
>
> > class Child(DeclarativeBase):
> > __tablename__ = 'child'
> > id = Column('id', types.Integer, primary_key=True,
> > nullable=False)
> > id_parent = Column('id_parent', types.Integer,
> > nullable=True)
> > parent = relation(Parent,
> > primaryjoin=id_parent==Parent.id,
> > foreign_keys=[Parent.id],
> > backref=backref('children',
> > foreign_keys=[id_parent],
> > cascade='all, delete-orphan',
> > passive_deletes=False))
>
> > p = Parent()
> > c = Child()
> > p.children.append(c)
> > DBSession.add(p)
> > DBSession.flush()
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