Datetime Timezones from String

Question

I am trying to figure out how to make a datetime object aware through using a variable. I grab the timezone of the user and pass it through a form to be used.

I have tried both of the below methods and am not having much success

timezone_variable = "Europe/London"
new_datetime = datetime(int(date_year), int(date_month), int(date_day),
                            int(time_hour), int(date_minute), tzinfo=timezone_variable)

new_datetime = datetime(int(date_year), int(date_month), int(date_day),
                            int(time_hour), int(date_minute), tzinfo=timezone.timezone_variable)

This will then give me errors of TypeError: tzinfo argument must be None or of a tzinfo subclass, not type 'str'

The timezone will not always be known upfront, so it would not be possible to simply have the argument be as such tzinfo=timezone.utc.

MattDMo · Answer 1 · 2020-10-22T03:09:23.810

3

You can create a timezone object from a string using pytz:

>>> from pytz import timezone
>>> timezone("Europe/London")
<DstTzInfo 'Europe/London' LMT-1 day, 23:59:00 STD>

This can then be used in the datetime.datetime() constructor as the tzinfo parameter. Use the localize() function as described in the docs if needed.

edited Oct 22 '20 at 03:09

answered Oct 21 '20 at 17:46

MattDMo

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FObersteiner · Accepted Answer · 2021-01-15T07:50:29.777

Using dateutil or Python 3.9's zoneinfo:

from datetime import datetime
from dateutil.tz import gettz
# from zoneinfo import ZoneInfo # Python 3.9

date_year, date_month, date_day, time_hour, date_minute = 2020, 10, 21, 10, 21

timezone_variable = gettz("Europe/London") # ZoneInfo("Europe/London") # Python 3.9

new_datetime = datetime(int(date_year), int(date_month), int(date_day),
                        int(time_hour), int(date_minute), tzinfo=timezone_variable)
print(new_datetime) 
# 2020-10-21 10:21:00+01:00 
print(repr(new_datetime))
# datetime.datetime(2020, 10, 21, 10, 21, tzinfo=tzfile('GB-Eire'))

# with zoneinfo:
# datetime.datetime(2020, 10, 21, 10, 21, tzinfo=zoneinfo.ZoneInfo(key='Europe/London'))

Note: you can directly create a datetime object. If you use pytz (deprecated with Python 3.9), you must use the localize method of the timezone object. Otherwise, you'll end up with LMT (local mean time):

import pytz
timezone_variable = pytz.timezone("Europe/London")

# not what you want (most of the time...):
new_datetime = datetime(int(date_year), int(date_month), int(date_day),
                        int(time_hour), int(date_minute), tzinfo=timezone_variable)
print(repr(new_datetime))
# datetime.datetime(2020, 10, 21, 10, 21, tzinfo=<DstTzInfo 'Europe/London' LMT-1 day, 23:59:00 STD>)

Side-note: interestingly, dateutil returns the deprecated GB-Eire time zone name for Europe/London. It is correct nevertheless, no worries.

Thanks. Do you know if there is anyway to localise an aware datetime? I have a datetime that is UTC timezone, and I want to convert it to a local timezone (unknown beforehand). I get an error trying to use localise, as it says it is aware, and as you said the .replace function gives LMT. — 101892781, Oct 21 '20 at 22:51
@101892781: answered [here](https://stackoverflow.com/q/64472668/10197418) ;-) — FObersteiner, Oct 22 '20 at 05:50

Datetime Timezones from String

2 Answers2