在Python中验证ISO-8601日期时间字符串? [英] Validate an ISO-8601 datetime string in Python?
问题描述
我想编写一个函数,该函数接受一个字符串并返回 True
(如果它是有效的ISO-8601日期时间,精确到微秒,包括时区偏移量) 错误
否则。
I want to write a function that takes a string and returns True
if it is a valid ISO-8601 datetime--precise to microseconds, including a timezone offset--False
otherwise.
我发现其他 问题,提供了不同的解析日期时间方式字符串,但仅在ISO-8601格式的情况下,我想返回 True
。除非我能使它抛出与ISO-8601不匹配的格式的错误,否则解析不会对我有帮助。
I have found other questions that provide different ways of parsing datetime strings, but I want to return True
in the case of ISO-8601 format only. Parsing doesn't help me unless I can get it to throw an error for formats that don't match ISO-8601.
(我正在使用漂亮的箭头库在我的代码的其他地方。使用 arrow
的解决方案
(I am using the nice arrow library elsewhere in my code. A solution that uses arrow
would be welcome.)
编辑:看来,有效的ISO 8601日期时间在常见的Python日期时间包中不存在。
It appears that a general solution to "is this string a valid ISO 8601 datetime" does not exist among the common Python datetime packages.
因此,为了使这个问题更窄,更具体和更易回答,我将选择一种格式将验证这种格式的日期时间字符串的字符串:
So, to make this question narrower, more concrete and answerable, I will settle for a format string that will validate a datetime string in this form:
'2016-12-13T21:20:37.593194+00:00'
当前我正在使用:
format_string = '%Y-%m-%dT%H:%M:%S.%f%z'
datetime.datetime.strptime(my_timestamp, format_string)
这给出了:
ValueError: time data '2016-12-13T21:20:37.593194+00:00' does not match format '%Y-%m-%dT%H:%M:%S.%f%z'
问题似乎在于UTC偏移量中的冒号( +00:00
)。如果我使用不带冒号的偏移量(例如’2016-12-13T21:20:37.593194 + 0000’
),则会按预期正确解析。这显然是因为 datetime
的%z
令牌不尊重带有冒号的UTC偏移格式,仅尊重不带有冒号的形式,即使这两个规范均有效。
The problem seems to lie with the colon in the UTC offset (+00:00
). If I use an offset without a colon (e.g. '2016-12-13T21:20:37.593194+0000'
), this parses properly as expected. This is apparently because datetime
's %z
token does not respect the UTC offset form that has a colon, only the form without, even though both are valid per the spec.
推荐答案
给出了许多用于验证日期和时间的ISO8601格式的变体(例如2008 -08-30T01:45:36或2008-08-30T01:45:36.123Z)。 XML Schema dateTime类型的正则表达式为:
give many variants for validating date and times in ISO8601 format (e.g., 2008-08-30T01:45:36 or 2008-08-30T01:45:36.123Z). The regex for the XML Schema dateTime type is given as:
>>> regex = r'^(-?(?:[1-9][0-9]*)?[0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])(\.[0-9]+)?(Z|[+-](?:2[0-3]|[01][0-9]):[0-5][0-9])?$'
所以为了验证您的身份可以做:
So in order to validate you could do:
import re
match_iso8601 = re.compile(regex).match
def validate_iso8601(str_val):
try:
if match_iso8601( str_val ) is not None:
return True
except:
pass
return False
一些示例:
>>> validate_iso8601('2017-01-01')
False
>>> validate_iso8601('2008-08-30T01:45:36.123Z')
True
>>> validate_iso8601('2016-12-13T21:20:37.593194+00:00')
True
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