Handling Timezones in Python
summary
Claims that naive datetimes cause up to 26 hours of ambiguity and that duration arithmetic must run in UTC; demonstrates actual code recipes using Python 3.9+ zoneinfo (or the backport plus tzdata) and Django settings (USE_TZ, timezone.activate, make_aware). Shows surprising pytz failure (example producing a UTC offset of 4h56m), gives concrete fixes: construct timezone-aware datetimes, store and compute in UTC, do calendar math on dates, convert to user timezone for display — code and slides provided.
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chapters (16)
- 0:00Start
- 0:44Motivation
- 2:59Outline
- 3:56Don't use naive datetimes
- 6:51Don't use dates without a timezone
- 8:35Don't do duration arithmetic outside of UTC
- 16:59Maximum compatibility
- 17:59Get current time
- 18:54Convert datetime to a date in a timezone
- 21:13Duration math on UTC datetimes
- 21:42Calendar math on dates
- 22:55Django timezone setup
- 23:38Templates automatically convert to localtime
- 24:25Converting to localtime
- 24:40Attaching a timezone to a naive datetime
- 25:14Summary
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