Em Qui, 2008-01-10 às 21:20 -0500, Rick Morrison escreveu:
> You're mixing single-table inheritance (using the discriminator
> column), with concrete inheritance (using multiple tables).
>
> You have to pick one scheme or the other. Either use a single
> inheritance chain, or separate the two class hierarchies into two
> separate chains that don't inherit from each other. In the separate
> scheme, each chain can use it's own discriminator column, but you
> cannot combine two class hierarchies that each use a different
> discriminator column.
hum, so something is wrong here, I recreate a simple test case and all
is working properly, using the exactly model suggested on my previous
message. I will debug my application to find where is the error, but for
now, I don't know if this should work, but is working.
here is the test case and results:
----code-----8<------code------
from sqlalchemy import create_engine, MetaData, Table, Column, types,
ForeignKey
from sqlalchemy.orm import mapper, relation, backref, create_session
from sqlalchemy import String, Unicode, Integer, DateTime, Numeric,
Boolean, UnicodeText
db = create_engine('sqlite:///:memory:')
metadata = MetaData()
metadata = MetaData(db)
metadata.bind = db
session = create_session(bind=db)
resource_table = Table('resource', metadata,
Column('id',Integer, primary_key=True),
Column('name', String(30)),
Column('poly', String(31), nullable=True)
)
person_table = Table('person', metadata,
Column('id',Integer, ForeignKey('resource.id'), primary_key=True,),
Column('poly', String(31), nullable=False)
)
material_table = Table('material', metadata,
Column('id',Integer, ForeignKey('resource.id'), primary_key=True,),
)
employee_table = Table('employee', metadata,
Column('id',Integer, ForeignKey('person.id'), primary_key=True),
)
technical_table = Table('technical', metadata,
Column('id',Integer, ForeignKey('person.id'), primary_key=True),
)
class Resource(object):
def __init__(self, name):
self.name = name
def __repr__(self):
return "Resource < id=%d ,name=%s >" % (self.id,self.name)
class Person(Resource):
def __repr__(self):
return "Person < id=%d ,name=%s >" % (self.id,self.name)
class Material(Resource):
def __repr__(self):
return "Material < id=%d ,name=%s >" % (self.id,self.name)
class Employee(Person):
def __repr__(self):
return "Employee < id=%d ,name=%s >" % (self.id,self.name)
class Technical(Person):
def __repr__(self):
return "Technical < id=%d ,name=%s >" % (self.id,self.name)
mapper(Resource, resource_table,
polymorphic_on=resource_table.c.poly,
polymorphic_identity='resource'
)
mapper(Person, person_table,
polymorphic_on=person_table.c.poly,
inherits=Resource, polymorphic_identity='person'
)
mapper(Material, material_table,
inherits=Resource, polymorphic_identity='material'
)
mapper(Employee, employee_table,
inherits=Person, polymorphic_identity='employee',
)
mapper(Technical, technical_table,
inherits=Person, polymorphic_identity='technical',
)
metadata.create_all(bind=db)
r = Resource('resource name')
p = Person('person name')
m = Material('material name')
e = Employee('employee name')
t = Technical('technical name')
session.save(r)
session.save(p)
session.save(m)
session.save(e)
session.save(t)
session.flush()
print "############ LIST FROM RESOURCES #################"
for o in session.query(Resource).all():
print o
print "############ LIST FROM PERSONS #################"
for o in session.query(Person).all():
print o
----code-----8<------code------
The results:
############ LIST FROM RESOURCES #################
Resource < id=1 ,name=resource name >
Person < id=2 ,name=person name >
Material < id=3 ,name=material name >
Employee < id=4 ,name=employee name >
Technical < id=5 ,name=technical name >
############ LIST FROM PERSONS #################
Person < id=2 ,name=person name >
Employee < id=4 ,name=employee name >
Technical < id=5 ,name=technical name >
I think it is working properly.
but I will try to remove the type columns
Thank's for help
--
Alexandre da Silva
Analista de Sistemas - Bacharel em Sistemas de Informação (2003-2007)
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