On 4-7-2012 22:29, Tomas Neme wrote:
> Besides that, if you don't want actual Base instances, then this is an
> abstract class, and you should do this:
>
> class Base(models.Model):
> eggs....
> plants....
> class Meta:
> abstract=True
>
> class Foo(Base):
> carpet=....
No, you /should/ not. You may do this, but you will end up with two
tables that /do not share the records/.
>From the OP's post it's obvious these classes share the data. Think of
Base as a table 'fruit' and the other two as apples and oranges. In this
case it doesn't make sense to duplicate the fruit data in the apples and
oranges table.
You would be using abstract models for much vaguer concepts, like I'm using:
class NamedEntity(models.Model) :
name = models.CharField(max_length=64, unique=True)
description = models.TextField()
class Meta :
abstract = True
ordering = [ 'name' ]
class Device(NamedEntity) :
interface = models.CharField(max_length=16)
# ....
class Category(NamedEntity) :
pass
In this case, you *want* device and category to be different tables for
the shared data as they represent totally different concepts and can
share names, but be totally different 'things' - like a 'cpu' category
with description 'central processor and supporting hardware' and a 'cpu'
device with description 'central processor device'.
--
Melvyn Sopacua
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