Python-сообщество

 class Account(Base):
    __tablename__ = 'account'
    id = Column(Integer, primary_key=True)
    taxes = relationship('Tax',
                         primaryjoin='and_(Account.id == Tax.account_id,'
                                     'Tax.removed == False)',
                         collection_class=attribute_mapped_collection('id'),
                         cascade='all')
    def create_tax(self, id_, name):
        c = Tax(id=id_, name=name)
        self.taxes[c.id] = c
    def remove_tax(self, id_):
        contribution = self.taxes[id_]
        contribution.removed = True
class Tax(Base):
    __tablename__ = 'tax'
    id = Column(Integer, primary_key=True)
    name = Column(String(50), nullable=False)
    account_id = Column(Integer, ForeignKey(Account.id), nullable=False)
    removed = Column(Boolean, nullable=False, default=False)
Base.metadata.drop_all(engine)
Base.metadata.create_all(engine)
if __name__ == '__main__':
    account = Account(id=1)
    account.create_tax(id_=1, name='General tax')
    account.create_tax(id_=2, name='Selective tax')
    assert len(account.taxes) == 2
    account.remove_tax(id_=1)
    assert len(account.taxes) == 1