How do I translate an ISO 8601 datetime string into a Python datetime object?

I prefer using the dateutil library for timezone handling and generally solid date parsing. If you were to get an ISO 8601 string like: 2010-05-08T23:41:54.000Z you'd have a fun time parsing that with strptime, especially if you didn't know up front whether or not the timezone was included. pyiso8601 has a couple of issues (check their tracker) that I ran into during my usage and it hasn't been updated in a few years. dateutil, by contrast, has been active and worked for me:

from dateutil import parser
yourdate = parser.parse(datestring)

Since Python 3.7 and no external libraries, you can use the fromisoformat function from the datetime module:

datetime.datetime.fromisoformat('2019-01-04T16:41:24+02:00')

Python 2 doesn't support the %z format specifier, so it's best to explicitly use Zulu time everywhere if possible:

datetime.datetime.strptime("2007-03-04T21:08:12Z", "%Y-%m-%dT%H:%M:%SZ")

Arrow looks promising for this:

>>> import arrow
>>> arrow.get('2014-11-13T14:53:18.694072+00:00').datetime
datetime.datetime(2014, 11, 13, 14, 53, 18, 694072, tzinfo=tzoffset(None, 0))

Arrow is a Python library that provides a sensible, intelligent way of creating, manipulating, formatting and converting dates and times. Arrow is simple, lightweight and heavily inspired by moment.js and requests.

You should keep an eye on the timezone information, as you might get into trouble when comparing non-tz-aware datetimes with tz-aware ones.

It's probably the best to always make them tz-aware (even if only as UTC), unless you really know why it wouldn't be of any use to do so.

#-----------------------------------------------
import datetime
import pytz
import dateutil.parser
#-----------------------------------------------

utc = pytz.utc
BERLIN = pytz.timezone('Europe/Berlin')
#-----------------------------------------------

def to_iso8601(when=None, tz=BERLIN):
  if not when:
    when = datetime.datetime.now(tz)
  if not when.tzinfo:
    when = tz.localize(when)
  _when = when.strftime("%Y-%m-%dT%H:%M:%S.%f%z")
  return _when[:-8] + _when[-5:] # Remove microseconds
#-----------------------------------------------

def from_iso8601(when=None, tz=BERLIN):
  _when = dateutil.parser.parse(when)
  if not _when.tzinfo:
    _when = tz.localize(_when)
  return _when
#-----------------------------------------------