django- 实现模型字段 每天 -1

from django.db import models
from datetime import datetime
class MyModel(models.Model):
    count = models.IntegerField()
    created_at = models.DateTimeField(auto_now_add=True)
    def save(self, *args, **kwargs):
        if not self.created_at:
            self.created_at = datetime.now()
        super().save(*args, **kwargs)
        # 每天自动减1
        current_date = datetime.now().date()
        yesterday_date = current_date - datetime.timedelta(days=1)
        if current_date != yesterday_date:
            self.count -= 1