Django fixtures save with default value

The solution was to use django signals:

import uuid
from django.db import models
from django.utils.translation import ugettext_lazy as _
from django.db.models.signals import pre_save
from django.dispatch import receiver

class Uuidable(models.Model):
    uuid = models.CharField(_('uuid'), blank=True,
                            null=False, unique=True,
                            max_length=64, default=uuid.uuid4())

    class Meta:
        abstract = True

    @receiver(pre_save)
    def set_uuid_on_save(sender, instance, *args, **kwargs):
        if instance.pk is None:
            instance.uuid = uuid.uuid4()

That way, the model/data is populated whatever way you create the model (via shell, fixtures, whatever).

Automatically loading initial data fixtures is deprecated in Django 1.7. One solution is via signals as you mentioned. Another one that I prefer is to create a python script where you create all the needed data, and execute it in the shell:

python manage.py shell < create_initial_data.py

I think that the problem is when you put default=uuid.uuid4(). The parenthesis are too much, because they imply that you pass the result of uuid.uuid4() to default argument and not the function itself, so you should put default=uuid.uuid4.