Tag Archives: Time Zone

Python

Python – Convert a timezone aware datetime to UTC datetime using pytz

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Previously:

 

If we have a datetime with timezone, we can also convert it to UTC datetime using pytz.

import pytz
import datetime

local_tz = pytz.timezone ("Asia/Hong_Kong")
datetime_without_tz = datetime.datetime.strptime("2015-02-14 12:34:56", "%Y-%m-%d %H:%M:%S")
datetime_with_tz = local_tz.localize(datetime_without_tz, is_dst=None) # No daylight saving time
datetime_in_utc = datetime_with_tz.astimezone(pytz.utc)

str1 = datetime_without_tz.strftime('%Y-%m-%d %H:%M:%S %Z')
str2 = datetime_with_tz.strftime('%Y-%m-%d %H:%M:%S %Z')
str3 = datetime_in_utc.strftime('%Y-%m-%d %H:%M:%S %Z')

print 'Without Timzone : %s' % (str1)
print 'With Timezone   : %s' % (str2)
print 'UTC Datetime    : %s' % (str3)

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Python

Python – Specify datetime timezone using pytz

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We can use the dateutil package to create timezone aware datetime.

 

We can also use the pytz to specify the timezone. Try the following example.

import pytz
import datetime

local_tz = pytz.timezone ("Asia/Hong_Kong")
datetime_without_tz = datetime.datetime.strptime("2015-02-14 12:34:56", "%Y-%m-%d %H:%M:%S")
datetime_with_tz = local_tz.localize(datetime_without_tz, is_dst=None) # No daylight saving time

str1 = datetime_without_tz.strftime('%Y-%m-%d %H:%M:%S %Z')
str2 = datetime_with_tz.strftime('%Y-%m-%d %H:%M:%S %Z')

print 'Without Timzone : %s' % (str1)
print 'With Timezone   : %s' % (str2)

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Python

Python – Create current datetime object with timezone

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Handling timezone is quite a pain in Python. When you create or read a datetime object, you need to make sure whether the datetime you need should be timezone aware or not.

Here is a simple example to create a datetime with timezone. The tzlocal will determine the timezone setting of the operating system and apply it to your datetime object.

import datetime
from dateutil.tz import tzlocal
 
now_without_tz = datetime.datetime.now()
now_with_tz    = datetime.datetime.now(tzlocal())

str1 = now_without_tz.strftime('%Y-%m-%d %H:%M:%S %Z')
str2 = now_with_tz.strftime('%Y-%m-%d %H:%M:%S %Z')
 
print 'Without Timzone : %s' % (str1)
print 'With Timezone   : %s' % (str2)

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Database

PostgreSQL – Set and Get Timezone

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There is a timezone configuration on PostgreSQL server. If you want to change the default globally, you can edit the postgresql.conf. On Ubuntu, it is located at

  • /etc/postgresql/<version>/main/postgresql.conf
# - Locale and Formatting -

datestyle = 'iso, mdy'
#intervalstyle = 'postgres'
#timezone = 'Hongkong'
timezone = 'UTC'

 

We could also tweak the timezone only in your current PostgreSQL session.

1. Get the current timezone.

SELECT current_setting('TIMEZONE');

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CakePHP

CakePHP – Apply Time Zone for Users

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Update @ 2012-09-25: This approach could not handle the DST zones. Thanks for the comment made by Lucas. =)

You can make use the TimeHelper to offset the time by user specified time zone. What u need is adding a new time_zone column in the users table just like the following example.

--MySQL
CREATE TABLE IF NOT EXISTS users (
	user_id INT NOT NULL auto_increment,
	name VARCHAR(45) NOT NULL,
	password VARCHAR(45) NOT NULL,
	time_zone DECIMAL(5,1) NOT NULL,
	created DATETIME DEFAULT NULL,
	PRIMARY KEY (user_id)
) ENGINE = InnoDB;

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