polymorphic/inheritance still glitchy with concrete/single table

concrete example:

from sqlalchemy import *

db = create_engine("sqlite:///:memory:")

metadata = BoundMetaData(db)
session = create_session()

class Employee(object):
    def __init__(self, name):
        self.name = name
    def __repr__(self):
        return self.__class__.__name__ + " " + self.name

class Manager(Employee):
    def __init__(self, name, manager_data):
        self.name = name
        self.manager_data = manager_data
    def __repr__(self):
        return self.__class__.__name__ + " " + self.name + " " +  self.manager_data

class Engineer(Employee):
    def __init__(self, name, engineer_info):
        self.name = name
        self.engineer_info = engineer_info
    def __repr__(self):
        return self.__class__.__name__ + " " + self.name + " " +  self.engineer_info


managers_table = Table('managers', metadata, 
    Column('employee_id', Integer, primary_key=True),
    Column('name', String(50)),
    Column('manager_data', String(50)),
).create()

engineers_table = Table('engineers', metadata, 
    Column('employee_id', Integer, primary_key=True),
    Column('name', String(50)),
    Column('engineer_info', String(50)),
).create()



pjoin = polymorphic_union({
    'manager':managers_table,
    'engineer':engineers_table
}, 'type', 'pjoin')

employee_mapper = mapper(Employee, pjoin, polymorphic_on=pjoin.c.type)
manager_mapper = mapper(Manager, managers_table, inherits=employee_mapper, concrete=True, polymorphic_identity='manager')
engineer_mapper = mapper(Engineer, engineers_table, inherits=employee_mapper, concrete=True, polymorphic_identity='engineer')



session.save(Manager('Tom', 'knows how to manage things'))
session.save(Engineer('Kurt', 'knows how to hack'))
session.flush()


# this gives you [Kurt knows how to hack, Manager Tom knows how to manage things](Engineer)
# as it should be
session.query(Employee).select()

# this fails
session.query(Engineer).select()

# this fails
session.query(Manager).select()

single table:

from sqlalchemy import *

db = create_engine("sqlite:///:memory:")

metadata = BoundMetaData(db)
session = create_session()

class Employee(object):
    def __init__(self, name):
        self.name = name
    def __repr__(self):
        return self.__class__.__name__ + " " + self.name

class Manager(Employee):
    def __init__(self, name, manager_data):
        self.name = name
        self.manager_data = manager_data
    def __repr__(self):
        return self.__class__.__name__ + " " + self.name + " " +  self.manager_data

class Engineer(Employee):
    def __init__(self, name, engineer_info):
        self.name = name
        self.engineer_info = engineer_info
    def __repr__(self):
        return self.__class__.__name__ + " " + self.name + " " +  self.engineer_info


employees_table = Table('employees', metadata, 
    Column('employee_id', Integer, primary_key=True),
    Column('name', String(50)),
    Column('manager_data', String(50)),
    Column('engineer_info', String(50)),
    Column('type', String(20))
)

employee_mapper = mapper(Employee, employees_table, polymorphic_on=employees_table.c.type)
manager_mapper = mapper(Manager, inherits=employee_mapper, polymorphic_identity='manager')
engineer_mapper = mapper(Engineer, inherits=employee_mapper, polymorphic_identity='engineer')


employees_table.create()

session.save(Manager('Tom', 'knows how to manage things'))
session.save(Engineer('Kurt', 'knows how to hack'))
session.flush()


# this gives you [Kurt knows how to hack, Manager Tom knows how to manage things](Engineer)
# as it should be
session.query(Employee).select()

# this gives you [Kurt knows how to hack, Manager Tom knows how to manage things](Engineer)
# instead of [Kurt knows how to hack](Engineer)
session.query(Engineer).select()


# this gives you [Kurt knows how to hack, Manager Tom knows how to manage things](Engineer)
# instead of [Tom knows how to manage things](Manager)
session.query(Manager).select()

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