Compare Difference Between Two Columns In SQLAlchemy ORM

I'm trying to find out how to do something like the answer to this question but using SQLAlchemy. Having a hard time finding how to order query results by the difference between t

Solution 1:

session.query((Table.revenue - Table.loss).label('profit')).order_by('profit desc').all()

For automatically calculate column you can use events

from sqlalchemy import event

class Table(Model):
    id = Column(Integer, primary_key=True)
    revenue = Column(Integer)
    loss = Column(Integer)
    profit = Column(Integer)

@event.listens_for(Table.revenue, 'set')
def revenue_listener(target, value, oldvalue, initiator):
    # update profit when revenue change
    target.profit = value - (target.loss or 0)

@event.listens_for(Table.loss, 'set')
def loss_listener(target, value, oldvalue, initiator):
    # update profit when loss change
    target.profit = (target.revenue or 0) - value