[Bug] Incorrect regex for xs:dateTime

[mjacoby]

See Bug description admin-shell-io/aas-specs#498

Relevant code

aas-core-meta/aas_core_meta/v3.py

Line 169 in 77d3442

timezone_frag = r"(Z|\+00:00|-00:00)"

[mristin]

Hi @mjacoby ,
This is the pattern for the date-time in UTC, an AAS-specific date time with the time zone fixed to UTC:

aas-core-meta/aas_core_meta/v3.py

Lines 148 to 178 in 77d3442

	def matches_xs_date_time_UTC(text: str) -> bool:
	"""
	Check that :paramref:`text` conforms to the pattern of an ``xs:dateTime``.
	The time zone must be fixed to UTC. We verify only that the ``text`` matches
	a pre-defined pattern. We *do not* verify that the day of month is
	correct nor do we check for leap seconds.
	See: https://www.w3.org/TR/xmlschema-2/#dateTime
	:param text: Text to be checked
	:returns: True if the :paramref:`text` conforms to the pattern
	"""
	digit = "[0-9]"
	year_frag = f"-?(([1-9]{digit}{digit}{digit}+)|(0{digit}{digit}{digit}))"
	month_frag = f"((0[1-9])|(1[0-2]))"
	day_frag = f"((0[1-9])|([12]{digit})|(3[01]))"
	hour_frag = f"(([01]{digit})|(2[0-3]))"
	minute_frag = f"[0-5]{digit}"
	second_frag = f"([0-5]{digit})(\\.{digit}+)?"
	end_of_day_frag = "24:00:00(\\.0+)?"
	timezone_frag = r"(Z|\+00:00|-00:00)"
	date_time_lexical_rep = (
	f"{year_frag}-{month_frag}-{day_frag}"
	f"T"
	f"(({hour_frag}:{minute_frag}:{second_frag})|{end_of_day_frag})"
	f"{timezone_frag}"
	)
	pattern = f"^{date_time_lexical_rep}$"
	return match(pattern, text) is not None

Note the function name matches_xs_date_time_UTC. The date-time from XSD with different time zones is defined in:

aas-core-meta/aas_core_meta/v3.py

Line 520 in 77d3442

def matches_xs_date_time(text: str) -> bool:

Following the issue the cause of: admin-shell-io/aas-specs#498, when you look at the relevant line in JSON schema:
https://github.com/admin-shell-io/aas-specs/blob/04a1f04b9748978767c21d765cb464249a818d2f/schemas/json/aas.json#L224

"pattern": "^-?(([1-9][0-9][0-9][0-9]+)|(0[0-9][0-9][0-9]))-((0[1-9])|(1[0-2]))-((0[1-9])|([12][0-9])|(3[01]))T(((([01][0-9])|(2[0-3])):[0-5][0-9]:([0-5][0-9])(\\.[0-9]+)?)|24:00:00(\\.0+)?)(Z|\\+00:00|-00:00)$"

, it corresponds to:

aas-core-meta/aas_core_meta/v3.py

Line 3824 in 77d3442

last_update: Optional["Date_time_UTC"]

so the pattern is correct (according to my understanding).

[mjacoby]

After having a closer look at things...I get what you are saying and I mostly agree.
The specification says the following for basicEventElement.lastUpdate

The issue here is that the Type is dateTime which is defined as xs:dateTime, meaning it can have any timezone. However, the explanation column states that the timestamp should/must(?) be in UTC. Based on that you introduced a new "type" Date_time_UTC. I would argue that the specification is wrong or at least inconsistent as the type information is constrained by the explanation to an undefined type "dateTimeUTC". The correct way to handle this would be to change the specification to either defined the type dateTimeUTC or to remove the UTC restriction in the explanation.

If you code is correct or not kinda depends on the interpretation of the specification because the type info says that it can contain any timezone but the explanation says it cannot.