How can I make django model datetime field data of midnight and timezone aware?

Question

I am trying to set expire_time in my django model to be midnight of user's selected date with timezone aware. But I am not able to get it properly. Can anyone tell me how I can do it or where I am making mistake in my code?

My codes are,

date = datetime.strptime(str(request.POST.get('expire') + ', 23:59:59'),
                                     '%Y-%m-%d, %H:%M:%S')
            tz = timezone.get_current_timezone()
            date_tz = tz.localize(date)
            createEventInDB.ev_expire = date_tz

            try:
                createEventInDB.save()

            except Exception as e:
                error = e

So if I select date which is December 1st 2015, it would be posting as 2015-12-1

I want to save data in database like 2015-12-01 23:59:59. I want to give whole day to user. My current timezone is America/Chicago. I have set active timezone by ip. So I want to make it like user can post from anywhere but timezone must be UTC aware and expire at midnight. Can anyone tell me how can I make it possible?

how do you know that your code is wrong? – jfs Nov 07 '15 at 06:39 — jfs, Nov 07 '15 at 06:39

Behzad · Answer 1 · 2015-11-07T09:00:40.507

2

based on the documentation at https://docs.djangoproject.com/en/1.8/topics/i18n/timezones/

When support for time zones is enabled, Django stores datetime information in UTC in the database, uses time-zone-aware datetime objects internally, and translates them to the end user’s time zone in templates and forms.

So all this is completely unnecessary and all you need to do is use the models.DateTimeField like you always did.

You can define a Date widget in the view or form and alter Time of DateTimeField later on to 23:59:59 before saving (or you can provide it as a default) and Django will automatically convert it to UTC before saving.

edited Nov 07 '15 at 09:00

answered Nov 07 '15 at 08:48

Behzad

89
7

it is wrong: *"alter Time of DateTimeField later on to 23:59:59 before saving"* -- if the given time and midnight use different utc offsets (e.g., they are across a DST transition) then you get a wrong UTC time as a result due to unnormalized input (that does not correspond to midnight anymore if you call `tz.normalize()` on it). See [How do I get the UTC time of “midnight” for a given timezone?](http://stackoverflow.com/q/373370/4279) – jfs Nov 07 '15 at 16:58
Both solutions are kinda helping but what I want to do is `2015-12-01 23:59:59 utc` in database. so user has whole 1st December. Or I can do is `2015-12-02 00:00:00 utc` – Django Learner Nov 07 '15 at 18:20
@J.F.Sebastian thanks for the link, it was helpful. (and also your username is awesome.) – Behzad Nov 07 '15 at 20:20

score 1 · Answer 2 · answered Nov 07 '15 at 20:28

I want to do is 2015-12-01 23:59:59 utc

Your code in the question returns 23:59:59 in the current time zone.

It is even simpler to return "23:59:59 UTC" instead given the corresponding UTC date:

from datetime import datetime
import pytz

ev_expire = datetime(utc_date.year, utc_date.month, utc_date.day, 23, 59, 59,
                     tzinfo=pytz.utc)

How can I make django model datetime field data of midnight and timezone aware?

2 Answers2