Ok looks reazonable. But be something like: p = Person(name='test') s = Student(person=p, course='test course')
or s = Student(parent=p) is desirable and easy to implement a copy data from Person instance to Student. On Jan 3, 1:02 am, Malcolm Tredinnick <malc...@pointy-stick.com> wrote: > On Fri, 2009-01-02 at 16:29 -0800, carlopires wrote: > > Hi, > > > I'm trying Multi Table Inheritance with: > > > class Person(models.Model): > > name = CharField(max_length=30) > > > class Student(Person): > > course = CharField(max_length=30) > > > on db shell: > > > p = Person(name='Carlo') > > p.save() > > > Why I can't: > > > s = Student(p) > > s.save() > > > ? > > How Can I evolute a Person to Student ? > > You can't. At least at the moment -- it's a sometimes requested feature, > but there are arguments against allowing it as well. Maybe one day we'll > add it. > > Realise that you can't do this in Python, either, which is why it's not > completely weird. If B is a subclass of A and you have an instance of A, > you cannot create an instance of B that is an evolved version without > copying all the data from the first instance into a new B instance. > That's exactly what you need to do here. Copy all the p items into the > Student constructor. So, in this way, model inheritance behaves like > Python (which is always the intention, as much as possible -- although > leaky abstractions interfere in both directions at times). > > Regards, > Malcolm > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~----------~----~----~----~------~----~------~--~---
