your metaclass must derive from the DeclarativeMeta class.
Also, I disagree that you need this metaclass, what you're trying to do is
very easy using mixins, which are supported in version 0.6:
http://docs.sqlalchemy.org/en/rel_0_6/orm/extensions/declarative.html#mixing-in-columns
On Jul 3, 2013, at 12:44 AM, Ven Karri <praveen.venk...@gmail.com> wrote:
> I use: Python 2.6 and sqlalchemy 0.6.1
>
> This is what I am trying to do:
>
> from sqlalchemy.types import (
> Integer,
> String,
> Boolean
> )
> from sqlalchemy.ext.declarative import declarative_base
>
> Base = declarative_base()
>
> class SampleMeta(type):
> def __new__(cls, name, bases, attrs):
> attrs.update({ 'id': Column('Id', Integer, primary_key=True),
> 'name': Column('Name', String),
> 'description': Column('Description', String),
> 'is_active': Column('IsActive', Boolean)
> })
> return super(SampleMeta, cls).__new__(cls, name, bases, attrs)
>
> class Sample(Base):
> __tablename__ = 'Sample'
> __table_args__ = {'useexisting': True}
> __metaclass__ = SampleMeta
>
> def __init__(self, id, name, description, is_active):
> self.id = id
> self.name = name
> self.description = description
> self.is_active = is_active
>
> def __repr__(self):
> return "<(%d, '%s', '%s', %r)>" % (self.id, self.name,
> self.description, self.isactive)
>
> And the error I am getting is this:
>
> TypeError: Error when calling the metaclass bases
> metaclass conflict: the metaclass of a derived class must be a
> (non-strict) subclass of the metaclasses of all its bases
>
> Now, if I do the same thing above by using
>
> class Sample(object)
>
> instead of
>
> class Sample(Base)
>
> it works absolutely fine.
>
> I need to update the attributes of the class dynamically. So, I will be using
> dynamic attribute and column names. And I need the above piece code to work
> in order to be able to get there.
>
> **Please help**
>
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