Access to the last object of model inside model itself

[Mohammad Etemaddar]

Hello

I need the last object of model inside it.

for example I have:

class Field(models.Model):

category = models.ForeignKey(Category, related_name='fields', on_delete=models.CASCADE,

default = get_last_factory_field_category())

def get_last_factory_field_category():

return Field.objects.last().category

In this definition, will get not defined error. because the function is defined after model.

preivously, I used lambda to get access to the last category. But makemigrations did not work while using lambda.

The clear problem is getting access to the last object of model inside of it.

[Jason]

This really should be in a custom model manager, and not the model itself.

[Mohammad Etemaddar]

Im not agree. Managers are created for custom query. But here the query is last.
I think I got the philosophy. The default value should not be a manager, because the database does not understand it.
Maybe I am wrong!

[Mohammad Etemaddar]

I commented out the default value and then ran the makemigrations again, and then uncommented again and worked. Of course by lambda.