Python Convert time to UTC format

Question

from django.utils import timezone
time_zone = timezone.get_current_timezone_name() # Gives 'Asia/Kolkata'
date_time = datetime.time(12,30,tzinfo=pytz.timezone(str(time_zone)))

Now I need to convert this time to UTC format and save it in Django model. I am not able to use date_time.astimezone(pytz.timezone('UTC')). How can I convert the time to UTC. Also Back to 'time_zone'.

This is a use case when user type time in a text box and we need to save time time in UTC format. Each user will also select his own time zone that we provide from Django timezone module.

Once the user request back the saved time it must be shown back to him in his selected time zone.

Solution

These things are always easier using complete datetime objects, e.g.:

import datetime
import pytz

time_zone = pytz.timezone('Asia/Kolkata')

# get naive date
date = datetime.datetime.now().date()
# get naive time
time = datetime.time(12, 30)
# combite to datetime
date_time = datetime.datetime.combine(date, time)
# make time zone aware
date_time = time_zone.localize(date_time)

# convert to UTC
utc_date_time = date_time.astimezone(pytz.utc)
# get time
utc_time = utc_date_time.time()

print(date_time)
print(utc_date_time)
print(utc_time)

Yields:

2014-07-13 12:30:00+05:30
2014-07-13 07:00:00+00:00
07:00:00

right now for me.

Comments

[Matt Johnson-Pint]

It shows +5:53:00 when it has not yet been applied to a datetime, because that's the earliest representation in the tzdb. The local mean time is usually calculated from solar observation, which reasonable aligns these old dates to our modern system.

[Matt Johnson-Pint]

Also, you should use localize instead of assigning the time zone to tzinfo directly. Read about localize in the pytz docs.

[famousgarkin]

@MattJohnson Thanks for feedback and +5:53 explanation! True that about localize. Updated the answer accordingly, now this is what we wanted.