我创建model必加的字段

class Category(models.Model):
    pub_date = models.DateTimeField('发布日期',auto_now_add=True)
    update_date = models.DateTimeField('更新日期',auto_now=True)
    sort = models.IntegerField("序号",default=99,help_text="序号越小越靠前")
    def __unicode__(self):
        return self.title
    def __str__(self):
        return self.title
    class Meta:
        verbose_name = '目录'
        verbose_name_plural = '0-目录'
        ordering = ['sort']  # 按照哪个栏目排序
        get_latest_by = 'pub_date'