Set default value of a field using classmethod in Django

Question

I've found many similar posts on the web about this topic but no one state clearly which is the problem.

Code

class Item(models.Model):
    @classmethod
    def get_next_item_number(cls):
        return cls.objects.count() + 1

    number = models.IntegerField(default=get_next_item_number)

Problem

When I access Django admin panel the text field related to 'number' field contains

<classmethod object at 0x7fab049d7c50>

So I tried to change the code above

class Item(models.Model):
    @classmethod
    def get_next_item_number(cls):
        return cls.objects.count() + 1

    number = models.IntegerField(default=get_next_item_number())

but when I run django server I get:

number = models.IntegerField(default=get_next_item_number())
TypeError: 'classmethod' object is not callable

I know all this could be prevented by declaring get_next_item_number() as an external function but this solution is not elegant to me because get_next_item_number() refer only to Item class.

Is there a solution I'm missing?

Answer 1

I found this solution:

Code

class Item(models.Model):
    @staticmethod
    def get_next_item_number():
        return Item.objects.count() + 1

    number = models.IntegerField(default=get_next_item_number.__func__)

I'm not completely aware of the possible consequences, but it works.