About Primary Keys of UUID Type

Don't set the default value for UUID primary keys, because it will be evaluated at initialization and you won't be able to easily check if an instance is already saved or not. Use the save() method instead to assign the value.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
import uuid
from django.db import models

class MyModel(models.Model):
    uuid = models.UUIDField(primary_key=True, default=None, editable=False)
    # …
    def save(self, *args, **kwargs):
        if self.pk is None:
            self.pk = uuid.uuid4()
        super().save(*args, **kwargs)

This way you can check in your Python code or templates:

1
2
3
4
if instance.pk:
    print("Object has been saved.")
else:
    print("Object is new.")

Tips and Tricks Programming Architecture Django 4.2 Django 3.2 Django 2.2

Also by me

Django Paddle Subscriptions app

For Django-based SaaS projects.

Django App for You
Django GDPR Cookie Consent app

For Django websites that use cookies.

Django App for You
Django 3 Web Development Cookbook - Fourth Edition
Book for You
Django 3 Web Development Cookbook

Learn how to build practical web projects with Django 3.
1st things 1st
SaaS for You
Online prioritizer "1st things 1st"

It's not for everyone, but it might be for you!