姜戈。如何在django模型中实现启动删除时间计数器或倒计时的逻辑来自动删除对象？

from django.db import models
from django.utils import timezone

class MyModel(models.Model):
    delete_time = models.DateTimeField(null=True, blank=True)

    def delete_after_time(self, hours):
        self.delete_time = timezone.now() + timezone.timedelta(hours=hours)
        self.save()

from django.db.models.signals import pre_save
from django.dispatch import receiver
from django.utils import timezone

from .models import MyModel

@receiver(pre_save, sender=MyModel)
def set_delete_time(sender, instance, **kwargs):
    if not instance.delete_time:
        instance.delete_time = timezone.now()

from datetime import datetime
from django.conf import settings
from django.utils import timezone
from django.core.management.base import BaseCommand
from django_apscheduler.jobstores import DjangoJobStore
from django_apscheduler.models import DjangoJobExecution
from apscheduler.schedulers.background import BackgroundScheduler

from .models import MyModel

def delete_expired_objects():
    now = timezone.now()
    expired_objects = MyModel.objects.filter(delete_time__lte=now)
    expired_objects.delete()

def start_scheduler():
    scheduler = BackgroundScheduler()
    scheduler.add_jobstore(DjangoJobStore(), "default")
    scheduler.add_job(delete_expired_objects, "interval", hours=1)
    scheduler.start()

class Command(BaseCommand):
    def handle(self, *args, **options):
        start_scheduler()

python manage.py run_scheduler