Field name "hiding" permitted now?

[parxier]

Hello, everyone!

I hope someone can help me here.

I'm trying to create an intermediate model hierarchy for data
migration purposes (I'm using South). Basically I want to move 'phone'
field (see below) from 'Call' model to its parent non-abstract
'Service' model and I need an intermediate state where this field
exists in both parent and child models. After reading this:
http://docs.djangoproject.com/en/1.1/topics/db/models/#field-name-hiding-is-not-permitted
I understand that it is not permitted to hide field name in child
model and django would raise a FieldError exception. And that's
exactly what happens:

class Phone(models.Model):
   pass

class Service(models.Model):
    phone = models.ForeignKey(Phone, related_name='services')

class Call(Service):
    phone = models.ForeignKey(Phone, related_name='calls')

> manage.py validate
django.core.exceptions.FieldError: Local field 'phone' in class 'Call'
clashes with field of similar name from base class 'Service'

works as expected... no problem

However, if I add new 'IntermediateService' model like this:

class Phone(models.Model):
   pass

class Service(models.Model):
    phone = models.ForeignKey(Phone, related_name='services')

class IntermediateService(Service):
    class Meta:
        abstract = True

class Call(IntermediateService):
    phone = models.ForeignKey(Phone, related_name='calls')

...surprisingly it validates:

> manage.py validate
0 errors found

and sqls for postgresql:
> manage.py sql app

CREATE TABLE "app_phone" (
    "id" serial NOT NULL PRIMARY KEY
);
CREATE TABLE "app_service" (
    "id" serial NOT NULL PRIMARY KEY,
    "phone_id" integer NOT NULL REFERENCES "app_phone" ("id")
DEFERRABLE INITIALLY DEFERRED
);
CREATE TABLE "app_call" (
    "service_ptr_id" integer NOT NULL UNIQUE REFERENCES
"app_service" ("id") DEFERRABLE INITIALLY DEFERRED,
    "phone_id" integer NOT NULL REFERENCES "app_phone" ("id")
DEFERRABLE INITIALLY DEFERRED
);

So what is it? Bug, hidden feature or what?

Thank you!

Vasily

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