Django 无法自动保存 DateTimeFields

Question

你好，我有一个这样的模型:

from datetime import datetime


class Project(models.Model):
    created = models.DateTimeField(editable=False)
    updated = models.DateTimeField(editable=False)
    product = models.ForeignKey('tool.product')
    module = models.ForeignKey('tool.module')
    model = models.ForeignKey('tool.model')
    zipcode = models.IntegerField(max_length=5)

    def save(self, **kwargs):
        if not self.id:
            self.created = datetime.now()
        self.updated = datetime.now()
        super(Project, self).save()

    def __unicode__(self):
        return self.id

但是，当我尝试保存项目时，我得到:

coercing to Unicode: need string or buffer, long found

来自运行服务器:

RuntimeWarning: DateTimeField received a naive datetime (2012-10-31 14:45:36.611622) while time zone support is active.

我不确定这里到底是什么问题，但我假设它与 timezone 妨碍保存 DateTimeField 有关。

如有任何帮助，我们将不胜感激。

Answer 1

首先 DateTimeField 支持这样的自动更新:

created = models.DateTimeField(editable=False, auto_now_add=True) # Only on creation
updated = models.DateTimeField(editable=False, auto_now=True)     # On every save

其次，您收到的 RuntimeWarning 意味着您已在您的settings.py 时区感知日期时间对象，例如您将看到以下内容:

USE_TZ = True

当你这样做时，你必须以不同的方式对待日期时间对象，你必须通过明确的 tzinfo 值。

# install the `pytz` module through pip or whatnot
from pytz import timezone
import datetime
from django.utils.timezone import utc

now = datetime.datetime.utcnow().replace(tzinfo=utc)

# To show the time in Greece
athens = timezone('Europe/Athens')
print now.astimezone(athens)

有关详细信息，请参阅 django docs和 pytz docs .

关于 coercing to Unicode: 错误，尝试这样做:

def __unicode__(self):
    return unicode(self.id)