[issue15873] datetime cannot parse ISO 8601 dates and times
Anders Hovmöller added the comment: Éric Araujo: absolutely. Although I think my code can be improved (speed wise, elegance, etc) since I just wrote it quickly a weekend :) -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15873 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15873] datetime cannot parse ISO 8601 dates and times
Éric Araujo added the comment: Are you offering the module for inclusion in the stdlib? -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15873 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15873] datetime cannot parse ISO 8601 dates and times
Anders Hovmöller added the comment: I've written a parser for ISO 8601: https://github.com/boxed/iso8601 Some basic tests are included and it supports most of the standard. Haven't gotten around to the more obscure parts like durations and intervals, but those are trivial to add... -- nosy: +Anders.Hovmöller ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15873 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15873] datetime cannot parse ISO 8601 dates and times
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[issue15873] datetime cannot parse ISO 8601 dates and times
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[issue15873] datetime cannot parse ISO 8601 dates and times
flying sheep added the comment: there is a module that parses those strings pretty nicely, it’s called pyiso8601: http://code.google.com/p/pyiso8601/ in the context of writing a better plistlib, i also needed the capability to parse those strings, and decided not to use the sucky incomplete implementation of plistlib, but the one mentioned above. i py3ified it, eliminating quite some code, and the result is pretty terse, check it out: https://github.com/flying-sheep/plist/blob/master/iso8601.py note that that implementation returns utc-datetimes for timezoneless strings, instead of naive ones. (l.30) -- nosy: +flying sheep ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15873 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15873] datetime cannot parse ISO 8601 dates and times
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[issue15873] datetime cannot parse ISO 8601 dates and times
Roy Smith added the comment: I've started collecting some test cases. I'll keep adding to the collection. I'm going to start trolling ISO 8601:2004(E) for more. Let me know if there are other sources I should be considering. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15873 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15873] datetime cannot parse ISO 8601 dates and times
Roy Smith added the comment: Ooops, clicked the wrong button. -- Added file: http://bugs.python.org/file27165/test-cases.py ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15873 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15873] datetime cannot parse ISO 8601 dates and times
Roy Smith added the comment: We need to define the scope of what input strings will be accepted. ISO-8601 defines a lot of stuff which we may not wish to accept. Do we want to accept both basic format (MMDD) and extended format (-MM-DD)? Do we want to accept things like 1985-W15-5, which is (if I understand this correctly(), the 5th day of the 15th week of 1985 [section 4.1.4.2]. Do we want to accept [section 4.2.2.4], 23:20,8, which is 23 hours, 20 minutes, 8 tenths of a minute. I suspect most people who have been following the recent thread (https://groups.google.com/d/topic/comp.lang.python/Q2w4R89Nq1w/discussion) would say none of the above are needed. All that's needed is if you have an existing datetime object, d1, you can do: s = str(d1) d2 = datetime.datetime(s) assert d1 == d2 for all values of d1. But, let's at least agree on that. Or, in the alternative, agree on something else. Then we know what we're shooting for. -- nosy: +roysmith ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15873 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15873] datetime cannot parse ISO 8601 dates and times
Alexander Belopolsky added the comment: On Sep 9, 2012, at 8:15 AM, Roy Smith rep...@bugs.python.org wrote: We need to define the scope of what input strings will be accepted. Since it is easier to widen the domain of acceptable arguments than to narrow it in the future, I would say let's start by accepting str(x) only where x is date, time, timezone or datetime. I would leave out timedelta for now because it's str(x) does not resemble ISO at all. Either that or full ISO 8601. Anything in between is just too hard to explain. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15873 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15873] datetime cannot parse ISO 8601 dates and times
Roy Smith added the comment: I see I mis-stated my example. When I wrote: s = str(d1) d2 = datetime.datetime(s) assert d1 == d2 what I really meant was: s = d1.isoformat() d2 = datetime.datetime(s) assert d1 == d2 But, now I realize that while that is certainly an absolute lower bound, it's almost certainly not sufficient. The most common use case I see on a daily basis is parsing strings that look like 2012-09-07T23:59:59+00:00. This is also John Nagle's original use case from the cited mailing list thread: I want to parse standard ISO date/time strings such as 2012-09-09T18:00:00-07:00 Datetime.isoformat() returns something that matches the beginning of that, but doesn't have the time zone offset. And it's the offset that makes strptime() not usable as a soluation, because %z isn't portable. If we don't satisfy the 2012-09-07T23:59:59+00:00 case, then we won't have really done anything useful. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15873 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15873] datetime cannot parse ISO 8601 dates and times
John Nagle added the comment: For what parts of ISO 8601 to accept, there's a standard: RFC3339, Date and Time on the Internet: Timestamps. See section 5.6: date-fullyear = 4DIGIT date-month = 2DIGIT ; 01-12 date-mday = 2DIGIT ; 01-28, 01-29, 01-30, 01-31 based on ; month/year time-hour = 2DIGIT ; 00-23 time-minute = 2DIGIT ; 00-59 time-second = 2DIGIT ; 00-58, 00-59, 00-60 based on leap second ; rules time-secfrac= . 1*DIGIT time-numoffset = (+ / -) time-hour : time-minute time-offset = Z / time-numoffset partial-time= time-hour : time-minute : time-second [time-secfrac] full-date = date-fullyear - date-month - date-mday full-time = partial-time time-offset date-time = full-date T full-time NOTE: Per [ABNF] and ISO8601, the T and Z characters in this syntax may alternatively be lower case t or z respectively. ISO 8601 defines date and time separated by T. Applications using this syntax may choose, for the sake of readability, to specify a full-date and full-time separated by (say) a space character. That's straightforward, and can be expressed as a regular expression. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15873 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15873] datetime cannot parse ISO 8601 dates and times
Alexander Belopolsky added the comment: I realize that while that is certainly an absolute lower bound, it's almost certainly not sufficient. The most common use case I see on a daily basis is parsing strings that look like 2012-09-07T23:59:59+00:00. This is exactly what isoformat() of an aware datetime looks like: datetime.now(timezone.utc).isoformat() '2012-09-09T16:09:46.165886+00:00' str() is the same up to T replaced by space: print(datetime.now(timezone.utc)) 2012-09-09 15:19:12.567692+00:00 -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15873 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15873] datetime cannot parse ISO 8601 dates and times
Alexander Belopolsky added the comment: For what parts of ISO 8601 to accept, there's a standard: RFC3339 This is almost indistinguishable from the idea of accepting .isoformat() and str() results. From what I see the only difference is that 't' is accepted for date/time separator and 'z' is accepted as a timezone. Let's start with this. As an ultimate solution, I would like to see something like codec registry so that we can do things like datetime(.., format='rfc3339') or date(.., format='gnu') for GNU parse_datetime. I think this will look more pythonic than strptime(). Of course, strptime format can also be accepted as the value for the format keyword. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15873 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15873] datetime cannot parse ISO 8601 dates and times
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[issue15873] datetime cannot parse ISO 8601 dates and times
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[issue15873] datetime cannot parse ISO 8601 dates and times
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[issue15873] datetime cannot parse ISO 8601 dates and times
New submission from John Nagle: The datetime module has support for output to a string of dates and times in ISO 8601 format (2012-09-09T18:00:00-07:00), with the object method isoformat([sep]). But there's no support for parsing such strings. A string to datetime class method should be provided, one capable of parsing at least the RFC 3339 subset of ISO 8601. The problem is parsing time zone information correctly. The allowed formats for time zone are empty - no TZ, date/time is naive in the datetime sense Z - zero, or Zulu time, i.e. UTC. [+-]nn.nn - offset from UTC strptime does not understand timezone offsets. The datetime documentation suggests that the z format directive handles time zone info, but that's not actually implemented for input. Pypi has four modules for parsing ISO 8601 dates. Each has least one major problem in time zone handling: iso8601 0.1.4 Abandonware. Mishandles time zone when time zone is Z and the default time zone is specified. iso8601.py 0.1dev Always returns a naive datetime object, even if zone specified. iso8601plus 0.1.6 Fork of abandonware version above. Same bug. zc.iso8601 0.2.0 Zope version. Imports the pytz module with the full Olsen time zone database, but doesn't actually use that database. Thus, nothing in Pypi provides a good alternative. It would be appropriate to handle this in the datetime module. One small, correct, tested function would be better than the existing five bad alternatives. -- components: Library (Lib) messages: 169941 nosy: nagle priority: normal severity: normal status: open title: datetime cannot parse ISO 8601 dates and times type: enhancement versions: Python 2.6, Python 2.7, Python 3.1, Python 3.2, Python 3.3, Python 3.4 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15873 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15873] datetime cannot parse ISO 8601 dates and times
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[issue15873] datetime cannot parse ISO 8601 dates and times
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[issue15873] datetime cannot parse ISO 8601 dates and times
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[issue15873] datetime cannot parse ISO 8601 dates and times
Alexander Belopolsky added the comment: %z format is supported, but it cannot accept colon in TZ offset. It can parse offsets like -0600 just fine. What OP is looking for is the GNU date %:z format which datetime does not support. For ISO 8601 compliance, however I think we need a way to specify a parser that will accept any valid 8601 format: with T or space separator and with or without : in time and timezone and with or without dashes in date. I would very much like such promiscuous parser to be implemented in datetime.__new__. So that we can create datetime objects from strings the way we do it with numbers. -- nosy: +Alexander.Belopolsky ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15873 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15873] datetime cannot parse ISO 8601 dates and times
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[issue15873] datetime cannot parse ISO 8601 dates and times
John Nagle added the comment: Re: %z format is supported. That's platform-specific; the actual parsing is delegated to the C library. It's not in Python 2.7 / Win32: ValueError: 'z' is a bad directive in format '%Y-%m-%dT%H:%M:%S%z' It really shouldn't be platform-specific; the underlying platform is irrelevant to this task. That's more of a documentation error; the features not common to all supported Python platforms should not be mentioned in the documentation. Re: I would very much like such promiscuous parser to be implemented in datetime.__new__. For string input, it's probably better to do this conversion in a specific class-level function. Full ISO 8601 dates/times generally come from computer-generated data via a file or API. If invalid text shows up, it should be detected as an error, not be heuristically interpreted as a date. There's already fromtimestamp and fromordinal, and isoformat as an instance method, so fromisoformat seems reasonable. I'd also suggest providing a standard subclass of tzinfo in datetime for fixed offsets. That's needed to express the time zone information in an ISO 8601 date. The new fromisoformat would convert an ISO 8601 date/time would be convertible to a time-zone aware datetime object. If converted back to an ISO 8601 string with .isoformat(), the round trip should preserve the original data, including time zone offset. (Several more implementations of this conversion have turned up. In addition to the four already mentioned, there was one in xml.util, and one in feedparser. There are probably more yet to be found.) -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15873 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15873] datetime cannot parse ISO 8601 dates and times
Alexander Belopolsky added the comment: On Thu, Sep 6, 2012 at 9:51 PM, John Nagle rep...@bugs.python.org wrote: It's not in Python 2.7 / Win32. Python 2.x series is closed and cannot accept new features. Both %z and fixed offset tzinfo subclass are implemented in 3.2. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15873 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue15873] datetime cannot parse ISO 8601 dates and times
Alexander Belopolsky added the comment: I am attaching a quick python only prototype for the proposed feature. My goal is to make date/time objects behave like numeric types for which constructors accept strings produced by str(). Since str() format is ISO 8601, it is natural to accept ISO 8601 formats in constructors. -- keywords: +patch Added file: http://bugs.python.org/file27141/issue15873-proto.diff ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue15873 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
