SQLAlchemy has wired problem of aliased.

sqlalchemy_polymorphic_aliased.py

#!/usr/bin/env python
from sqlalchemy import Column, Integer, create_engine, case, func, String, cast
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker, aliased

engine = create_engine('sqlite://', echo=True)
Base = declarative_base()


class Number(Base):
    __tablename__ = 'table'
    id = Column(Integer, primary_key=True, autoincrement=True)
    # set polymorphic 
    __mapper_args__ = {'polymorphic_on': id % 2}


class Even(Number):
    __mapper_args__ = {'polymorphic_identity': 0}


class Odd(Number):
    __mapper_args__ = {'polymorphic_identity': 1}


Base.metadata.create_all(engine)

Session = sessionmaker(bind=engine)
session = Session()

session.add(Number())
session.add(Number())
session.commit()

# without aliased
assert [i.id for i in session.query(Number).order_by(Number.id)] == [1, 2]

# aliased version
# this will raise sqlalchemy.exc.NoSuchColumnError:
# "Could not locate column in row for column 'table_1.id % :param_1'"
number_aliased = aliased(Number)
assert [
    i.id for i in session.query(number_aliased).order_by(number_aliased.id)
] == [1, 2]