spacepaste

from sqlalchemy import Column, String, ForeignKeyConstraint, Integer
from sqlalchemy.ext.declarative import declarative_base, declared_attr
class TableName(object):
@declared_attr
def __tablename__(cls):
return cls.__name__
Base=declarative_base(cls=TableName)
class TMixin(object):
@declared_attr
def user(cls):
return Column(String, primary_key=True)
@declared_attr
def timestamp(cls):
return Column(Integer, autoincrement=False, primary_key=True)
class Timeline(TMixin, Base):
snaptype = Column(Integer, primary_key=True, autoincrement=False)
__mapper_args__ = {'polymorphic_on': snaptype}
class CMixin(TMixin):
@declared_attr
def __table_args__(cls):
return (ForeignKeyConstraint(
['user', 'timestamp'],
['Timeline.user', 'Timeline.timestamp']),)
@declared_attr
def __mapper_args__(cls):
return {'polymorphic_identity': CMixin.__subclasses__().index(cls)}
class C(CMixin, Timeline):
pass