Python Datetime Utc

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  1. Python Datetime Utc Timestamp
  2. Python Datetime To Utc
  3. Python Datetime Utcnow
  4. Python Datetime Utc Format
  5. Python Datetime Utcnow

#!/usr/bin/env python3 import datetime print ('Local Date and Time: ',datetime.datetime.now) print ('Current Date and Time for UTC Timezone: ',datetime.datetime.now(datetime.timezone.utc)) We can also write this script in the following format, by importing only the required sub module from datetime module. An example of Python now to get current local date and time. The following example displays the current local date and time by using the now function of the datetime. For that, you first need to import datetime module, as shown in the example below. Python datetime provides tzinfo, which is an abstract base class that allows datetime.datetime and datetime.time to include time zone information, including an idea of daylight saving time. However, datetime does not provide a direct way to interact with the IANA time zone database.

TL;DR: You should always store datetimes in UTC and convert to proper timezone on display.

Python Datetime Utc

A timezone offset refers to how many hours the timezone is from Coordinated Universal Time (UTC). The offset of UTC is +00:00, and the offset of Asia/Taipei timezone is UTC+08:00 (you could also present it as GMT+08:00). Basically, there is no perceptible difference between Greenwich Mean Time (GMT) and UTC.

The local time subtracts the offset of its timezone is UTC time. For instance, 18:00+08:00 of Asia/Taipei minuses timezone offset +08:00 is 10:00+00:00, 10 o'clock of UTC. On the other hand, UTC time pluses local timezone offset is local time.

ref:
https://opensource.com/article/17/5/understanding-datetime-python-primer
https://julien.danjou.info/blog/2015/python-and-timezones

到底是 GMT+8 還是 UTC+8?
http://pansci.asia/archives/84978

Installation

Show System Timezone

ref:
https://github.com/regebro/tzlocal
https://stackoverflow.com/questions/13218506/how-to-get-system-timezone-setting-and-pass-it-to-pytz-timezone/

Find Timezones Of A Certain Country

ref:
https://pythonhosted.org/pytz/#country-information

Offset-naive Datetime

Any naive datetime would be present as local timezone but without tzinfo, so it is buggy.

A naive datetime object contains no timezone information. The datetime_obj.tzinfo will be set to None if the object is naive. Actually, datetime objects without timezone should be considered as a 'bug' in your application. It is up for the programmer to keep track of which timezone users are working in.

ref:
https://docs.python.org/3/library/datetime.html
https://dateutil.readthedocs.io/en/stable/

Offset-aware Datetime

A aware datetime object embeds a timezone information. Rules of thumb for timezone in Python:

  • Always work with 'offset-aware' datetime objects.
  • Always store datetime in UTC and do timezone conversion only when interacting with users.
  • Always use ISO 8601 as input and output string format.

There are two useful methods: pytz.utc.localize(naive_dt) for converting naive datetime to timezone be offset-aware, and aware_dt.astimezone(pytz.timezone('Asia/Taipei')) for adjusting timezones of offset-aware objects.

You should avoid naive_dt.astimezone(some_tzinfo) which would be converted to aware datetime as system timezone then convert to some_tzinfo timezone.

For working with pytz, it is recommended to call tz.localize(naive_dt) instead of naive_dt.replace(tzinfo=tz). dt.replace(tzinfo=tz) does not handle daylight savings time correctly.

ref:
https://pythonhosted.org/pytz/

Naive and aware datetime objects are not comparable.

Parse String to Datetime

Utc

python-dateutil usually comes in handy.

ref:
https://dateutil.readthedocs.io/en/stable/

Convert Datetime To Unix Timestamp

Convert

Python Datetime Utc Timestamp

Parse Unix Timestamp To Datetime

ref:
https://stackoverflow.com/questions/13890935/does-pythons-time-time-return-the-local-or-utc-timestamp

We might receive an Unix timestamp from a JavaScript client.

Python Datetime To Utc

ref:
https://momentjs.com/docs/#/parsing/unix-timestamp/

Store Datetime In Databases

Python Datetime Utcnow

  • MySQL lets developers decide what timezone should be used, and you should convert datetime to UTC before saving into database.
  • MongoDB assumes that all the timestamp are in UTC, and you have to normalize datetime to UTC.

ref:
https://tommikaikkonen.github.io/timezones/
https://blog.elsdoerfer.name/2008/03/03/fun-with-timezones-in-django-mysql/

Python Datetime Utc Format

Tools

Python Datetime Utcnow

ref:
https://www.epochconverter.com/
https://www.timeanddate.com/worldclock/converter.html