Convert zulu time string to MST datetime object

Question

How can I convert this string to MST timezone datetime object?

>>> type(date_str)
<type 'str'>
>>> date_str
'2017-01-17T20:02:45.767Z'

Answer 1

Here's a Python 3.9 option, using the standard lib only:

from datetime import datetime
from zoneinfo import ZoneInfo

date_str = '2017-01-17T20:02:45.767Z'

# to datetime, UTC:
dt = datetime.fromisoformat(date_str.replace('Z', '+00:00'))

# to mountain standard time:
dt_mountain = dt.astimezone(ZoneInfo("America/Denver"))

print(dt_mountain.isoformat())
# 2017-01-17T13:02:45.767000-07:00

For older versions, a different approach using dateutil:

from datetime import datetime
import dateutil

date_str = '2017-01-17T20:02:45.767Z'

# to datetime, UTC:
dt = dateutil.parser.parse(date_str)

# to mountain standard time:
dt_mountain = dt.astimezone(dateutil.tz.gettz("America/Denver"))

print(dt_mountain.isoformat())
# 2017-01-17T13:02:45.767000-07:00

Answer 2

This is an ISO 8601 compliant string. There are various libraries that can convert this. But to combine this with a Timezone conversion, you can:

import datetime as dt
from pytz import timezone

def convert_my_iso_8601(iso_8601, tz_info):
    assert iso_8601[-1] == 'Z'
    iso_8601 = iso_8601[:-1] + '000'
    iso_8601_dt = dt.datetime.strptime(iso_8601, '%Y-%m-%dT%H:%M:%S.%f')
    return iso_8601_dt.replace(tzinfo=timezone('UTC')).astimezone(tz_info)

my_dt = convert_my_iso_8601('2017-01-17T20:02:45.767Z', timezone('MST'))