django日期比较

from django.db import models
from django.utils import timezone
import datetime# Create your models here.
class Question(models.Model):
question_text=models.CharField(max_length=200)
pub_date=models.DateTimeField('date published')
def __str__(self): # __unicode__ on Python 2
return self.question_text
def was_published_recently(self):
# return self.pub_date >= timezone.now()- datetime.timedelta(days=1)
if self.pub_date >= timezone.now()- datetime.timedelta(days=3):
return 'new'
else:
return 'old'