import uuid
from django.db import models

class BaseModel(models.Model):
    """
    Abstract base model that uses a UUID for its primary key instead of an integer.
    """
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)

    class Meta:
        abstract = True

class TimeStampedModel(BaseModel):
    """
    Abstract base model that adds self-updating created_at and updated_at fields.
    """
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        abstract = True