How to make a datetime object aware (not naive)

DST-aware timezone handling with Pytz

Dealing with timezones as well as daylight saving time (DST)? Don't skip the pytz library:

from datetime import datetime
import pytz

naive_datetime = datetime.now()
timezone_aware_datetime = pytz.timezone('America/New_York').localize(naive_datetime)
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In this case, localize properly adjusts for DST, an aspect that replace won't cover. That's right, replace is the 'conference call in your pyjamas' of datetime manipulation!

Python 3.9's integrated solution

Who needs third-party libraries when you have Python 3.9 or later?

from datetime import datetime
from zoneinfo import ZoneInfo

naive_datetime = datetime.now()
timezone_aware_datetime = naive_datetime.replace(tzinfo=ZoneInfo('America/New_York'))
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Python 3.9's zoneinfo is the hot and fresh meal you eat in your kitchen, while pytz is the takeout you order when you can't cook!

For Python versions 3.6-3.8, don't fret; backports.zoneinfo is available to cook the same delicious meal!

Converting aware datetimes between timezones

Want to convert between timezones? The astimezone method has got your back:

from datetime import datetime, timezone
from zoneinfo import ZoneInfo  # Python 3.9+

aware_datetime = datetime.now(timezone.utc)
new_timezone = aware_datetime.astimezone(ZoneInfo("Asia/Tokyo"))
print(new_timezone)
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This exquisite method respects timezone transitions for that unique DST flavour and serves up the same absolute moment in time. And there's nothing like UTC to serve as a pro default choice for timezone-unaware datetimes!

Local system's timezone

If you want to align with your system's timezone, use ZoneInfo('localtime'):

from datetime import datetime
from zoneinfo import ZoneInfo

local_aware_datetime = datetime.now(ZoneInfo('localtime'))
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Windows users might feel left out; just remember to include the tzdata package to get your system's updated timezone database. Python on Windows, it's like pineapple on a pizza, some people swear by it!

ISO format for storing and comparing aware datetimes

To keep the datetime output human-friendly, ISO format steps in:

aware_datetime_iso = timezone_aware_datetime.isoformat()
print(aware_datetime_iso)
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It's the babbling brook of datetime representation, cruising with all the timezone information for precise calculations.

Advanced timezone functionalities with external libraries

If you require greater timezone functionalities, specific external modules like dateutil or Arrow can run that extra mile:

from dateutil import parser

aware_datetime = parser.parse('2022-03-05T12:30:00+02:00')
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