DateTime and ISO8601

philkime has asked for the wisdom of the Perl Monks concerning the following question:

I need to use DateTime::Format::ISO8601 but there is a problem I come across with DateTime in general in that it fills in missing month/days instead of leaving them undef:

use DateTime::Format::ISO8601;
my $dt = DateTime::Format::ISO8601->parse_datetime('2016');
say join(',', $dt->year, $dt->month, $dt->day);
my $dt = DateTime::Format::ISO8601->parse_datetime('2016-01-01');
say join(',', $dt->year, $dt->month, $dt->day);
[download]

Outputs:

2016,1,1
2016,1,1
[download]

If I need to know whether there was a month/day in the input, the information is lost. Of course I could parse the input date myself to find this out but this is not lazy enough when there is a module that's supposed to be doing this for me. Any comments on this? I need some of the era functionality of DT but this issue prevents me from being able to use it at the moment.

Comment on DateTime and ISO8601 Select or Download Code

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Re: DateTime and ISO8601 by SBECK (Chaplain) on May 19, 2016 at 20:13 UTC
This is not precisely what you are looking for, but I'll offer it as an alternative. I found the same problem when I was adding support for ISO8601 dates to Date::Manip, and I wanted to find out which fields had been set. Date::Manip (which will parse all of the ISO8601 dates) has a method (complete) which will tell you what fields were explicitly added, and which are implied. So you end up with: `use Date::Manip::Date; my $obj = new Date::Manip::Date; $obj->parse("2000-06-01-00:00"); print $obj->value(),"\n"; print $obj->complete('h'),"\n"; print $obj->complete('m'),"\n"; print $obj->complete('s'),"\n";` [download] prints: `2000060100000 1 1 0` [download] So, if you can't get DateTime to do it, you may want to look at Date::Manip.	[reply] [d/l] [select]
Re^2: DateTime and ISO8601 by philkime (Beadle) on May 19, 2016 at 20:47 UTC
Ah, thank you, last time I looked at Date::Manip, I don't think ->complete() was in there. The tricky part is that I need DateTime's era (BC/AD etc) output support.	[reply]