models.py

from django.db import models
from django.utils import timezone
""" Source: https://twitter.com/JackDLinke/status/1578435998492475392/photo/1"""

class ItemQuerySet(self):
    """Used to return a QuerySet that has been filtered"""

    def expired_items(self):
        return self.filter(expired_isnull=True)


class ItemManager(models.Manager):
    """Used for table-level methods that do NOT return a QuerySet"""

    def delete_expired_items(self):
        self.expired_items().delete()

    def get_queryset(self):
        """Limit every query used with this Queryset / Manager to critical Items"""
        return super().get_queryset().filter(critical=True)


class Item(models.Model):
    critical = models.BooleanField(default=True)
    expired = models.DateTimeField(blank=True, null=True)

    # Uses the `from_queryset` method to combine Manager and QuerySet
    # https://docs.djangoproject.com/en/4.1/topics/db/managers/#from-queryset
    CombinedItemManager = ItemManager.from_queryset(ItemQuerySet)
    objects = CombinedItemManager()

    # Optional additional manager with no query filter limitations
    unscoped = models.Manager()

    def expire_item(self):
        self.expired = timezone.now()
        self.save()


# Returns all critical items
Item.objects.all()

# Returns all critical items that are expired
Item.objects.expired_items()

# Expire a single item
item = Item.objects.first()
item.expire_item()

# Deletes any critical  Items that are expired
Item.objects.delete_expired_items()