New submission from Bengt Lüers <bengt.lue...@gmail.com>:
I am trying to parse ISO8601-formatted datetime strings with timezones.
This works fine when there is a colon separating the hour and minute digits:
>>> import datetime
>>> datetime.datetime.fromisoformat('2020-11-16T11:00:00+00:00')
>>> datetime.datetime(2020, 11, 16, 11, 0, tzinfo=datetime.timezone.utc)
However this fails when there is no colon between the hour and the minute
digits:
>>> import datetime
>>> datetime.datetime.fromisoformat('2020-11-16T11:00:00+0000')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: Invalid isoformat string: '2020-11-16T11:00:00+0000'
This behavior is unexpected, as the ISO8601 standard allows omitting the colon
in the string and defining the timezone as "<time>±hhmm
":
https://en.wikipedia.org/wiki/ISO_8601#Time_offsets_from_UTC
As a workaround, I normalized the timezone suffixes before parsing:
>>> if iso8601_string.endswith('+0000'):
>>> return iso8601_string[:-len('+0000')] + '+00:00'
>>> if iso8601_string.endswith('+00'):
>>> return iso8601_string[:-len('+00')] + '+00:00'
>>> if iso8601_string.endswith('-0000'):
>>> return iso8601_string[:-len('-0000')] + '+00:00'
>>> if iso8601_string.endswith('-00'):
>>> return iso8601_string[:-len('-00')] + '+00:00'
This only works for the UTC timezone. I would be nice to have a more general
solution which can handle any timezone.
I tested this with CPython 3.8. `.fromisoformat()` was added in 3.7, so earlier
versions should not be affected by this:
https://docs.python.org/3/library/datetime.html#datetime.date.fromisoformat
----------
components: Library (Lib)
messages: 381102
nosy: Bengt.Lüers
priority: normal
severity: normal
status: open
title: Missing colon in timezone suffix raises ValueError
type: behavior
versions: Python 3.8
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue42371>
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