如何标注查询集自创建以来的天数

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

class MyModel(models.Model):
    created_at = models.DateTimeField(auto_now_add=True)

# 假设有一个名为MyModel的模型，包含一个名为created_at的字段，记录创建日期

# 查询集标注自创建以来的天数
from django.db.models import F, ExpressionWrapper
from django.db.models.functions import Now

days_since_created = ExpressionWrapper(
    Now() - F('created_at'),
    output_field=models.DurationField()
)

queryset = MyModel.objects.annotate(days_since_created=days_since_created)