Why does Python 3 find this ISO8601 date: "2019-04-05T16:55:26Z" invalid?

Question

I supply "2019-04-05T16:55:26Z" to Python 3's datetime.datetime.fromisoformat and get Invalid isoformat string, though the same string works without the Z. ISO8601 allows for the Z - https://en.wikipedia.org/wiki/ISO_8601

$ python3
Python 3.7.2 (default, Feb 12 2019, 08:15:36)

>>> datetime.fromisoformat("2019-04-05T16:55:26Z")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: Invalid isoformat string: '2019-04-05T16:55:26Z'

>>> datetime.fromisoformat("2019-04-05T16:55:26")
datetime.datetime(2019, 4, 5, 16, 55, 26)

Possible duplicate https://stackoverflow.com/questions/19654578/python-utc-datetime-objects-iso-format-doesnt-include-z-zulu-or-zero-offset — Nick Vitha, Apr 05 '19 at 19:39
[The docs](https://docs.python.org/3/library/datetime.html#datetime.datetime.fromisoformat) clearly state what's supported. — jonrsharpe, Apr 05 '19 at 19:40
Yes they do, but perhaps the name is misleading given that they don't work with the actual ISO format! — stephendwolff, Apr 06 '19 at 20:04

score 33 · Answer 1 · edited Apr 05 '19 at 19:43

33

I just checked the Python 3 documentation and it isn't intended to parse arbitrary ISO8601 format strings:

Caution: This does not support parsing arbitrary ISO 8601 strings - it is only intended as the inverse operation of datetime.isoformat().

edited Apr 05 '19 at 19:43

jonrsharpe

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answered Apr 05 '19 at 19:40

stephendwolff

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Ok, but then what would be the proper function to parse this string? – Barney Szabolcs Oct 01 '19 at 14:53
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@BarnabasSzabolcs, my point exactly - i responded to jonrsharpe above with 'the name is misleading given they don't work with the actual ISO format' – stephendwolff Oct 02 '19 at 15:03

score 24 · Answer 2 · answered Apr 07 '22 at 07:40

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If you already know the format your API responds, you can use:

from datetime import datetime
datetime.strptime("2022-04-07T08:53:42.06717+02:00", "%Y-%m-%dT%H:%M:%S.%f%z")

Adjust for your needs, if the string for example does not contain milliseconds, etc.

Otherwise, as the official python documentation suggests, use the dateutil package: https://dateutil.readthedocs.io/en/stable/parser.html#dateutil.parser.isoparse

answered Apr 07 '22 at 07:40

NicoHood

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Wow, `dateutil` is brand new to me. This saves me a lot of time, thank you! – Joe Sadoski May 26 '22 at 20:30
`dateutil` is the proper way to do ti – Andres Canella Jan 19 '23 at 22:59

score 6 · Answer 3 · answered Feb 19 '23 at 11:42

6

Proper ISO format including the timezone is now supported in 3.11

https://docs.python.org/3.11/library/datetime.html#datetime.datetime.fromisoformat

answered Feb 19 '23 at 11:42

regoawt

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score 1 · Answer 4 · answered Aug 04 '23 at 08:42

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I had the same issue and solve it based in this answer.

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

It returns a datetime.datetime so is perfect.

answered Aug 04 '23 at 08:42

J Agustin Barrachina

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score -15 · Answer 5 · answered Jun 16 '21 at 18:04

-15

It is so simple. Just remove the last letter Z.

>>> from datetime import datetime; datetime.fromisoformat("2019-04-05T16:55:26")
datetime.datetime(2019, 4, 5, 16, 55, 26)

answered Jun 16 '21 at 18:04

dom free

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i think you might be missing the point somewhat – stephendwolff Sep 23 '21 at 20:02
are you sure this even works correctly in other timezones? – SOFe Jan 19 '23 at 07:46

Why does Python 3 find this ISO8601 date: "2019-04-05T16:55:26Z" invalid?

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