class Contact(models.Model):
content_type =
models.ForeignKey(ContentType,editable=False,null=True)
def save(self):
if(not self.content_type):
self.content_type =
ContentType.objects.get_for_model(self.__class__)
self.save_base()
def as_leaf_class(self):
content_type = self.content_type
model = content_type.model_class()
if(model == Contact):
return self
return model.objects.get(id=self.id)
note that this would reload the object from database.
if you merely want to find out what animal it is, then you can just
check animal.content_type
use a debug middleware footer so that you can check what queries are
actually performed.
http://www.djangosnippets.org/snippets/1031/
On Sep 7, 1:54 pm, dozo <[EMAIL PROTECTED]> wrote:
> I've run into the following problem with model inheritance, and I
> can't find a reasonable way to solve it:
>
> Let's say I have an Animal model, with a few subclasses: Lion, Tiger,
> Zebra and so on. The Animal model is not abstract, because I want to
> be able to, say, select all the animals in the database.
>
> So now I want to go over a collection of animals and determine whether
> each one is a Lion or a Tiger (or an Elephant, a Zebra and so on...)
>
> If I do this:
> animals = Animal.objects.all()
> I get a list of objects of type Animal. Each one will have a .tiger
> attribute or a .lion attribute according to its subclass, so
> apparently it "knows" what subclass it belongs to. But I can find no
> way of determining its subclass in a generic manner.
>
> To clarify, I would like to be able to do something like this:
>
> animals = Animal.objects.all()
> for animal in animals:
> animal_type = ...
> print "I am a", animal_type
>
> and get:
> I am a Zebra
> I am a Lion
> etc.
>
> Any ideas?
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