this was a bug in 0.5.0rc4 and is fixed in 0.5.0.
On Jan 6, 2:49 pm, Gennady Kovalev <gennady.kova...@gmail.com> wrote:
> Hi!
>
> I try to clean up my code, and read in google group about possibility
> create relation to self when class is not defined yet. I write
> example,
> but got an error (see below).
>
> My code is:
> ================ cut ====================
> engine = create_engine('sqlite:///:memory:', echo=True)
> Base = declarative_base(bind=engine)
>
> class Node(Base):
> __tablename__ = 'node'
> id = Column(Integer, primary_key=True)
> title = Column(String(64))
> node_id = Column(Integer, ForeignKey('node.id'))
> children = relation('Node', \
> backref=backref('parent', remote_side='Node.id'))
>
> Base.metadata.create_all()
>
> Session = scoped_session( \
> sessionmaker(autocommit=False, \
> autoflush=False, bind=engine))
> session = Session()
>
> root = Node(title='root')
> node = Node(title='node')
> root.children.append(node)
>
> session.save(root)
> session.commit()
> ================ cut ====================
>
> Workaround worked correctly:
>
> class Node(Base):
> # define attrs without `children'
> # ...
>
> Node.__mapper__.add_property('children', relation(Node, \
> backref=backref('parent', remote_side=Node.id)))
>
> Last traceback lines (formated):
>
> ...
> File "...orm/properties.py", line 578, in do_init
> self._determine_local_remote_pairs()
> File "...orm/properties.py", line 820, in
> _determine_local_remote_pairs
> self.local_side, self.remote_side = \
> [util.OrderedSet(x) for x in zip(*list(self.local_remote_pairs))]
>
> ValueError: need more than 0 values to unpack
>
> (self.local_remote_pairs is `[]' here)
>
> Can I define relation inside non-defined class, or I must use some
> workarounds?
>
> Thank you.
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