模型上只有两个字段，一个用于创建，另一个用于记录更新时间，如下所示

class Location(models.Model):
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

如果你使用django-model-utils，你可以子类化TimeStampedModel，它有创建和修改字段。

#Django model utils TimeStampedModel
class TimeStampedModel(models.Model):
    """
    An abstract base class model that provides self-updating
    ``created`` and ``modified`` fields.

    """
    created = AutoCreatedField(_('created'))
    modified = AutoLastModifiedField(_('modified'))

    class Meta:
        abstract = True

class Location(TimeStampedModel):
    """
    Add additional fields
    """