On Aug 13, 2009, at 9:23 PM, allen.fowler wrote:
>
>
>
> On Aug 13, 2:37 pm, Anton Gritsay <gene...@angri.ru> wrote:
>> Hi, Allen!
>>
>> You can use something like this (yeah, I know that it isn't
>> declarative in any way):
>>
>> class Node(Base):
>> __tablename__ = 'node'
>> id = Column(Integer, primary_key=True)
>> parent_id = Column(ForeignKey('node.id'))
>>
>> parent = relation("Node", remote_side=[id])
>>
>> mp_path = Column(sqlamp.PathField())
>> mp_depth = Column(sqlamp.DepthField())
>> mp_tree_id = Column(sqlamp.TreeIdField())
>>
>> Node.mp = sqlamp.MPManager(
>> Node.__table__,
>> pk_field='id',
>> parent_id_field='parent_id',
>> path_field_name='mp_path',
>> depth_field_name='mp_depth',
>> tree_id_field_name='mp_tree_id'
>> )
>> Node.__mapper__.extension.append(Node.mp.mapper_extension)
>>
>> Note that you need to define mp_* colums. You doesn't need it if you
>> create MPManager *before* creating mapper.
>>
>
>
>
> Anton,
>
>
> Thank you for the help. And the excellent library. :)
>
> I will try this code out as soon as I can.
>
> Michael B:
> Is this the only way to register such an extension with declarative
> base? Can a simpler method be devised?
err well if you wanted to cut down on verbosity possibly a custom
metaclass that descends from DeclarativeMeta, or sqlamp can build some
kind of "deferred" system bywhich the mapper extension figures out
what it needs from the mapper passed to it...since the extension is
dependent on the table object nothing spectacular is apparent otherwise.
>
>
> -- AF
> >
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