DateTime::Format::ISO8601(3p)

NAME
DateTime::Format::ISO8601 - Parses ISO8601 formats

VERSION
version 0.19

SYNOPSIS
    use DateTime::Format::ISO8601;

    my $datetime_str = '2020-07-25T11:32:31';
    my $dt = DateTime::Format::ISO8601->parse_datetime($datetime_str);
    say $dt;

    # This format is ambiguous and could be either a date or time, so use the
    # parse_time method.
    my $time_str = '113231';
    $dt = DateTime::Format::ISO8601->parse_time($time_str);
    say $dt;

    # or

    my $iso8601 = DateTime::Format::ISO8601->new;
    $dt = $iso8601->parse_datetime($datetime_str);
    say $dt;

    $dt = $iso8601->parse_time($time_str);
    say $dt;

    say DateTime::Format::ISO8601->format_datetime($dt);

DESCRIPTION
Parses almost all ISO8601 date and time formats. ISO8601 time-intervals will be supported in a later release.

METHODS
This class provides the following methods:

  Constructors
DateTime::Format::ISO8601->new( ... )

Accepts an optional hash.

    my $iso8601 = DateTime::Format::ISO8601->new(
        base_datetime => $dt,
        cut_off_year  => 42,
        legacy_year   => 1,
    );

•   base_datetime

    A "DateTime" object that will be used to fill in missing information from incomplete date/time formats.

    This key is optional.

•   cut_off_year

    A integer representing the cut-off point between interpreting 2-digits years as 19xx or 20xx.

        2-digit years <  cut_off_year will be interpreted as 20xx
        2-digit years >= cut_off_year will be untreated as 19xx

    This key defaults to the value of "DefaultCutOffYear".

•   legacy_year

    A boolean value controlling if a 2-digit year is interpreted as being in the current century (unless a "base_datetime" is set) or if "cut_off_year" should be used to place the year in either 20xx or 19xx.

    If this is true, then the "cut_off_year" is used. If this is false, then the year is always interpreted as being in the current century.

    This key defaults to the value of "DefaultLegacyYear".

$iso8601->clone

Returns a replica of the given object.

  Object Methods
$iso8601->base_datetime

Returns a "DateTime" object if a "base_datetime" has been set.

$iso8601->set_base_datetime( object => $object )

Accepts a "DateTime" object that will be used to fill in missing information from incomplete date/time formats.

$iso8601->cut_off_year

Returns a integer representing the cut-off point between interpreting 2-digits years as 19xx or 20xx.

$iso8601->set_cut_off_year($int)

Accepts a integer representing the cut-off point between interpreting 2-digits years as 19xx or 20xx.

    2-digit years <  legacy_year will be interpreted as 20xx
    2-digit years >= legacy_year will be interpreted as 19xx

$iso8601->legacy_year

Returns a boolean value indicating the 2-digit year handling behavior.

$iso8601->set_legacy_year($bool)

Accepts a boolean value controlling if a 2-digit year is interpreted as being in the current century (unless a "base_datetime" is set) or if "cut_off_year" should be used to place the year in either 20xx or 19xx.

  Class Methods
DateTime::Format::ISO8601->DefaultCutOffYear($int)

Accepts a integer representing the cut-off point for 2-digit years when calling "parse_*" as class methods and the default value for "cut_off_year" when creating objects. If called with no parameters this method will return the default value for "cut_off_year".

DateTime::Format::ISO8601->DefaultLegacyYear($bool)

Accepts a boolean value controlling the legacy year behavior when calling "parse_*" as class methods and the default value for "legacy_year" when creating objects. If called with no parameters this method will return the default value for "legacy_year".

  Parser(s)
These methods may be called as either class or object methods.

parse_datetime

parse_time

Please see the "FORMATS" section.

  Formatter
This may be called as either class or object method.

format_datetime($dt)

Formats the datetime in an ISO8601-compatible format. This differs from "iso8601" in DateTime by including nanoseconds/milliseconds and the correct timezone offset.

FORMATS
There are 6 strings that can match against date only or time only formats. The "parse_datetime" method will attempt to match these ambiguous strings against date only formats. If you want to match against the time only formats use the "parse_time" method.

  Conventions

•   Expanded ISO8601

    These formats are supported with exactly 6 digits for the year. Support for a variable number of digits will be in a later release.

•   Precision

    If a format doesn't include a year all larger time unit up to and including the year are filled in using the current date/time or [if set] the "base_datetime" object.

•   Fractional time

    There is no limit on the expressed precision.

    Note: sub-nanosecond times are truncated.

  Supported via parse_datetime
The supported formats are listed by the section of ISO 8601:2000(E) in which they appear.

5.2 Dates

•   5.2.1.1

    YYYYMMDD
    YYYY-MM-DD

•   5.2.1.2

    YYYY-MM
    YYYY
    YY

•   5.2.1.3

    YYMMDD
    YY-MM-DD
    -YYMM
    -YY-MM
    -YY
    --MMDD
    --MM-DD
    --MM
    ---DD

•   5.2.1.4

    +[YY]YYYYMMDD
    +[YY]YYYY-MM-DD
    +[YY]YYYY-MM
    +[YY]YYYY
    +[YY]YY

•   5.2.2.1

    YYYYDDD
    YYYY-DDD

•   5.2.2.2

    YYDDD
    YY-DDD
    -DDD

•   5.2.2.3

    +[YY]YYYYDDD
    +[YY]YYYY-DDD

•   5.2.3.1

    YYYYWwwD
    YYYY-Www-D

•   5.2.3.2

    YYYYWww
    YYYY-Www
    YYWwwD
    YY-Www-D
    YYWww
    YY-Www
    -YWwwD
    -Y-Www-D
    -YWww
    -Y-Www
    -WwwD
    -Www-D
    -Www
    -W-D

•   5.2.3.4

    +[YY]YYYYWwwD
    +[YY]YYYY-Www-D
    +[YY]YYYYWww
    +[YY]YYYY-Www

5.3 Time of Day

•   5.3.1.1 - 5.3.1.3

    Values can optionally be prefixed with 'T'.

•   5.3.1.1

    hh:mm:ss

•   5.3.1.2

    hh:mm

•   5.3.1.3 - 5.3.1.4

    fractional (decimal) separator maybe either ',' or '.'

•   5.3.1.3

    hhmmss,ss
    hh:mm:ss,ss
    hhmm,mm
    hh:mm,mm
    hh,hh

•   5.3.1.4

    -mm:ss
    -mmss,s
    -mm:ss,s
    -mm,m
    --ss,s

•   5.3.3 - 5.3.4.2

    Values can optionally be prefixed with 'T'.

•   5.3.3

    hhmmssZ
    hh:mm:ssZ
    hhmmZ
    hh:mmZ
    hhZ
    hhmmss.ssZ
    hh:mm:ss.ssZ

•   5.3.4.2

    hhmmss[+-]hhmm
    hh:mm:ss[+-]hh:mm
    hhmmss[+-]hh
    hh:mm:ss[+-]hh
    hhmmss.ss[+-]hhmm
    hh:mm:ss.ss[+-]hh:mm

5.4 Combinations of date and time of day

•   5.4.1

    YYYYMMDDThhmmss
    YYYY-MM-DDThh:mm:ss
    YYYYMMDDThhmmssZ
    YYYY-MM-DDThh:mm:ssZ
    YYYYMMDDThhmmss[+-]hhmm
    YYYY-MM-DDThh:mm:ss[+-]hh:mm
    YYYYMMDDThhmmss[+-]hh
    YYYY-MM-DDThh:mm:ss[+-]hh

•   5.4.2

    YYYYMMDDThhmmss.ss
    YYYY-MM-DDThh:mm:ss.ss
    YYYYMMDDThhmmss.ss[+-]hh
    YYYY-MM-DDThh:mm:ss.ss[+-]hh
    YYYYMMDDThhmmss.ss[+-]hhmm
    YYYY-MM-DDThh:mm:ss.ss[+-]hh:mm

•   5.4.3

    Support for this section is not complete.

    YYYYMMDDThhmm
    YYYY-MM-DDThh:mm
    YYYYMMDDThhmmZ
    YYYY-MM-DDThh:mmZ
    YYYYDDDThhmm
    YYYY-DDDThh:mm
    YYYYDDDThhmmZ
    YYYY-DDDThh:mmZ
    YYYYWwwDThhmm[+-]hhmm
    YYYY-Www-DThh:mm[+-]hh

5.5 Time-Intervals

These are not currently supported

  Supported via parse_time
5.3.1.1 - 5.3.1.3

Values can optionally be prefixed with 'T'.

•   5.3.1.1

    hhmmss

•   5.3.1.2

    hhmm
    hh

•   5.3.1.4

    -mmss
    -mm
    --ss

STANDARDS DOCUMENT

  Title
    ISO8601:2000(E)
    Data elements and interchange formats - information exchange -
    Representation of dates and times
    Second edition 2000-12-15

  Reference Number
    ISO/TC 154 N 362

CREDITS
Iain 'Spoon' Truskett (SPOON) who wrote DateTime::Format::Builder. That has grown into The Vacuum Energy Powered "Swiss Army" Katana of date and time parsing. This module was inspired by and conceived in honor of Iain's work.

Tom Phoenix (PHOENIX) and PDX.pm for helping me solve the ISO week conversion bug. Not by fixing the code but motivation me to fix it so I could participate in a game of "Zendo".

Jonathan Leffler (JOHNL) for reporting a test bug.

Kelly McCauley for a patch to add 8 missing formats.

Alasdair Allan (AALLAN) for complaining about excessive test execution time.

Everyone at the DateTime "Asylum".

SEE ALSO

•   DateTime

•   DateTime::Format::Builder

SUPPORT
Bugs may be submitted at <https://github.com/houseabsolute/DateTime-Format-ISO8601/issues>.

SOURCE
The source code repository for DateTime-Format-ISO8601 can be found at <https://github.com/houseabsolute/DateTime-Format-ISO8601>.

AUTHORS

•   Joshua Hoblitt <josh@hoblitt.com>

•   Dave Rolsky <autarch@urth.org>

CONTRIBUTORS

•   Doug Bell <doug@preaction.me>

•   joe <draxil@gmail.com>

•   Liam Widdowson <lbw@telstra.com>

•   Thomas Klausner <domm@plix.at>

•   Timothy Legge <timlegge@gmail.com>

•   William Ricker <bill.n1vux@gmail.com>

COPYRIGHT AND LICENSE
This software is copyright (c) 2026 by Joshua Hoblitt.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

The full text of the license can be found in the LICENSE file included with this distribution.