Python UTC datetime object's ISO format doesn't include Z (Zulu or Zero offset)


Why python 2.7 doesn't include Z character (Zulu or zero offset) at the end of UTC datetime object's isoformat string unlike JavaScript?

>>> datetime.datetime.utcnow().isoformat()

Whereas in javascript

>>>  console.log(new Date().toISOString()); 

This question is tagged with python python-2.7 datetime timestamp iso8601

~ Asked on 2013-10-29 09:42:06

The Best Answer is


Python datetime objects don't have time zone info by default, and without it, Python actually violates the ISO 8601 specification (if no time zone info is given, assumed to be local time). You can use the pytz package to get some default time zones, or directly subclass tzinfo yourself:

from datetime import datetime, tzinfo, timedelta
class simple_utc(tzinfo):
    def tzname(self,**kwargs):
        return "UTC"
    def utcoffset(self, dt):
        return timedelta(0)

Then you can manually add the time zone info to utcnow():

>>> datetime.utcnow().replace(tzinfo=simple_utc()).isoformat()

Note that this DOES conform to the ISO 8601 format, which allows for either Z or +00:00 as the suffix for UTC. Note that the latter actually conforms to the standard better, with how time zones are represented in general (UTC is a special case.)

~ Answered on 2014-05-16 22:54:38


Option: isoformat()

Python's datetime does not support the military timezone suffixes like 'Z' suffix for UTC. The following simple string replacement does the trick:

In [1]: import datetime

In [2]: d = datetime.datetime(2014, 12, 10, 12, 0, 0)

In [3]: str(d).replace('+00:00', 'Z')
Out[3]: '2014-12-10 12:00:00Z'

str(d) is essentially the same as d.isoformat(sep=' ')

See: Datetime, Python Standard Library

Option: strftime()

Or you could use strftime to achieve the same effect:

In [4]: d.strftime('%Y-%m-%dT%H:%M:%SZ')
Out[4]: '2014-12-10 12:00:00Z'

Note: This option works only when you know the date specified is in UTC.

See: datetime.strftime()

Additional: Human Readable Timezone

Going further, you may be interested in displaying human readable timezone information, pytz with strftime %Z timezone flag:

In [5]: import pytz

In [6]: d = datetime.datetime(2014, 12, 10, 12, 0, 0, tzinfo=pytz.utc)

In [7]: d
Out[7]: datetime.datetime(2014, 12, 10, 12, 0, tzinfo=<UTC>)

In [8]: d.strftime('%Y-%m-%d %H:%M:%S %Z')
Out[8]: '2014-12-10 12:00:00 UTC'

~ Answered on 2017-03-14 03:59:40

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