On Wed, Nov 25, 2009 at 7:10 PM, jedie <google...@jensdiemer.de
> On 25 Nov., 00:36, Russell Keith-Magee <freakboy3...@gmail.com
>> Why would it be? A datetime field isn't necessarily stored in UTC. It
>> uses datetime.now() because that will return the same time as
> To improve my understanding: What if the server changed and the time
> zone is not the same? IMHO the user can choose: 1. leave the
> settings.TIME_ZONE to the old value, so all old datetimes are right,
> but new datetimes are wrong. Or 2. he can update settings.TIME_ZONE
> and old datetimes would be wrong, but new are right. Isn't it?
If the server changes, then it's up to the admin to manage that
change. Django *won't* make a change that will silently destroy the
integrity of existing databases in the field just by updating code,
which is *exactly* what changing to utcnow would do. Right now, there
are *thousands* of Django installations in the field - including many
of my own - that rely on the fact that auto_now uses datetime.now()
and returns a time localized to TIME_ZONE.
This behavior may be flawed, but it doesn't change the fact that this
is the way it currently is.
Storing datetimes in UTC may be a better default strategy, but that
doesn't change the way it currently is.
I am in complete agreement that Django should have better support for
time zones. As Rob Hudson pointed out, there is a long-standing ticket
requesting this (#2626). Changing the behavior of auto_now to return
utcnow doesn't address the larger problem.
>> On top of that, making this change would be a *huge* backwards
>> incompatibility, as any existing uses of auto_now etc would break.
> Yes. But it's easy to add a settings and the admin can choose between
> now or utcnow. The default settings should be set utcnow.
No, on two counts.
1. Adding a setting to fix a problem doesn't fix a problem. It adds a
2. The existing value is datetime.now. *If* we were to add such a
setting (and let me tell you right now - we aren't going to), the
default value *must* be to use datetime.now - otherwise you don't get
backwards compatibility by default.
Russ Magee %-)