> -----Original Message----- > From: sqlalchemy@googlegroups.com > [mailto:sqlalch...@googlegroups.com] On Behalf Of Jules Stevenson > Sent: 13 July 2010 15:01 > To: sqlalchemy@googlegroups.com > Subject: [sqlalchemy] Problem with Joined Table inheritance > > Apologies for any stupidity, but I'm struggling with some joined table > inheritance, I have the following code: > > widgets_table = sa.Table('web_widgets', meta.metadata, > sa.Column('widget_id', sa.types.Integer, primary_key=True), > sa.Column('title',sa.types.String(length=255)), > sa.Column('widget_type', sa.types.String(30), nullable=False), > sa.Column('position', sa.types.Integer), > sa.Column('page_id', sa.types.Integer, > sa.ForeignKey('web_pages.id')) > ) > > video_widget_table = sa.Table('web_video_widget', meta.metadata, > sa.Column('widget_id', sa.types.Integer, > sa.ForeignKey('web_widgets.widget_id'), primary_key=True), > sa.Column('teaser', sa.types.String(length=10000)), > sa.Column('body',sa.types.String(length=21845)), > sa.Column('image', sa.types.String(length=256)) > ) > > class ArkWebWidget(object): > def __init__(self): > pass > > class ArkWebVideoWidget(object): > def __init__(self): > pass > > > orm.mapper(ArkWebWidget, widgets_table, > polymorphic_on=widgets_table.c.widget_type, > polymorphic_identity='widget' > ) > > orm.mapper(ArkWebVideoWidget, video_widget_table, > inherits=ArkWebWidget, > polymorphic_identity='video_widget' > ) > > --------------------------- > > However, when I run this I get an error: > > ... > File > "C:\ark\env_x64\lib\site-packages\sqlalchemy-0.6.2-py2.6.egg\s > qlalchemy\o > rm\__init__.py", line 818, in mapper > return Mapper(class_, local_table, *args, **params) > File > "C:\ark\env_x64\lib\site-packages\sqlalchemy-0.6.2-py2.6.egg\s > qlalchemy\o > rm\mapper.py", line 207, in __init__ > self._configure_inheritance() > File > "C:\ark\env_x64\lib\site-packages\sqlalchemy-0.6.2-py2.6.egg\s > qlalchemy\o > rm\mapper.py", line 231, in _configure_inheritance > (self.class_.__name__, self.inherits.class_.__name__)) > sqlalchemy.exc.ArgumentError: Class 'ArkWebVideoWidget' does > not inherit from 'A > rkWebWidget' > > And I'm really not sure what I've done wrong, it seems ok based on > what is written in the docs? > > Any pointers much appreciated. > > Jules >
I think the error message is quite explicit - you need to make your ArkWebVideoWidget class inherit from ArkWebWidget. At the moment, it inherits from 'object'. http://www.sqlalchemy.org/docs/mappers.html#mapping-class-inheritance-hi erarchies Notice that the Manager and Engineer classes both inherit from Employee. Hope that helps, Simon -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalch...@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.
