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aniso8601

Another ISO 8601 parser for Python

Features

  • Pure Python implementation
  • Python 3 support
  • Logical behavior
  • UTC offset represented as fixed-offset tzinfo
  • Parser separate from representation, allowing parsing to different datetime formats
  • No regular expressions

Installation

The recommended installation method is to use pip:

$ pip install aniso8601

Alternatively, you can download the source (git repository hosted at Bitbucket) and install directly:

$ python setup.py install

Use

Parsing datetimes

To parse a typical ISO 8601 datetime string:

>>> import aniso8601
>>> aniso8601.parse_datetime('1977-06-10T12:00:00Z')
datetime.datetime(1977, 6, 10, 12, 0, tzinfo=+0:00:00 UTC)

Alternative delimiters can be specified, for example, a space:

>>> aniso8601.parse_datetime('1977-06-10 12:00:00Z', delimiter=' ')
datetime.datetime(1977, 6, 10, 12, 0, tzinfo=+0:00:00 UTC)

UTC offsets are supported:

>>> aniso8601.parse_datetime('1979-06-05T08:00:00-08:00')
datetime.datetime(1979, 6, 5, 8, 0, tzinfo=-8:00:00 UTC)

If a UTC offset is not specified, the returned datetime will be naive:

>>> aniso8601.parse_datetime('1983-01-22T08:00:00')
datetime.datetime(1983, 1, 22, 8, 0)

Leap seconds are currently not supported and attempting to parse one raises a LeapSecondError:

>>> aniso8601.parse_datetime('2018-03-06T23:59:60')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "aniso8601/time.py", line 131, in parse_datetime
    return builder.build_datetime(datepart, timepart)
  File "aniso8601/builder.py", line 300, in build_datetime
    cls._build_object(time))
  File "aniso8601/builder.py", line 71, in _build_object
    ss=parsetuple[2], tz=parsetuple[3])
  File "aniso8601/builder.py", line 253, in build_time
    raise LeapSecondError('Leap seconds are not supported.')
aniso8601.exceptions.LeapSecondError: Leap seconds are not supported.

Parsing dates

To parse a date represented in an ISO 8601 string:

>>> import aniso8601
>>> aniso8601.parse_date('1984-04-23')
datetime.date(1984, 4, 23)

Basic format is supported as well:

>>> aniso8601.parse_date('19840423')
datetime.date(1984, 4, 23)

To parse a date using the ISO 8601 week date format:

>>> aniso8601.parse_date('1986-W38-1')
datetime.date(1986, 9, 15)

To parse an ISO 8601 ordinal date:

>>> aniso8601.parse_date('1988-132')
datetime.date(1988, 5, 11)

Parsing times

To parse a time formatted as an ISO 8601 string:

>>> import aniso8601
>>> aniso8601.parse_time('11:31:14')
datetime.time(11, 31, 14)

As with all of the above, basic format is supported:

>>> aniso8601.parse_time('113114')
datetime.time(11, 31, 14)

A UTC offset can be specified for times:

>>> aniso8601.parse_time('17:18:19-02:30')
datetime.time(17, 18, 19, tzinfo=-2:30:00 UTC)
>>> aniso8601.parse_time('171819Z')
datetime.time(17, 18, 19, tzinfo=+0:00:00 UTC)

Reduced accuracy is supported:

>>> aniso8601.parse_time('21:42')
datetime.time(21, 42)
>>> aniso8601.parse_time('22')
datetime.time(22, 0)

A decimal fraction is always allowed on the lowest order element of an ISO 8601 formatted time:

>>> aniso8601.parse_time('22:33.5')
datetime.time(22, 33, 30)
>>> aniso8601.parse_time('23.75')
datetime.time(23, 45)

Leap seconds are currently not supported and attempting to parse one raises a LeapSecondError:

>>> aniso8601.parse_time('23:59:60')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "aniso8601/time.py", line 116, in parse_time
    return _RESOLUTION_MAP[get_time_resolution(timestr)](timestr, tz, builder)
  File "aniso8601/time.py", line 165, in _parse_second_time
    return builder.build_time(hh=hourstr, mm=minutestr, ss=secondstr, tz=tz)
  File "aniso8601/builder.py", line 253, in build_time
    raise LeapSecondError('Leap seconds are not supported.')
aniso8601.exceptions.LeapSecondError: Leap seconds are not supported.

Parsing durations

To parse a duration formatted as an ISO 8601 string:

>>> import aniso8601
>>> aniso8601.parse_duration('P1Y2M3DT4H54M6S')
datetime.timedelta(428, 17646)

Reduced accuracy is supported:

>>> aniso8601.parse_duration('P1Y')
datetime.timedelta(365)

A decimal fraction is allowed on the lowest order element:

>>> aniso8601.parse_duration('P1YT3.5M')
datetime.timedelta(365, 210)

The decimal fraction can be specified with a comma instead of a full-stop:

>>> aniso8601.parse_duration('P1YT3,5M')
datetime.timedelta(365, 210)

Parsing a duration from a combined date and time is supported as well:

>>> aniso8601.parse_duration('P0001-01-02T01:30:5')
datetime.timedelta(397, 5405)

The relative kwarg is deprecated and will be removed in aniso8601 5.0.0, use builder=RelativeTimeBuilder instead.

The above treat years as 365 days and months as 30 days. If calendar level accuracy is required, the provided RelativeTimeBuilder can be used if dateutil is installed:

>>> import aniso8601
>>> from aniso8601.builder import RelativeTimeBuilder
>>> from datetime import date
>>> one_month = aniso8601.parse_duration('P1M', builder=RelativeTimeBuilder)
>>> two_months = aniso8601.parse_duration('P2M', builder=RelativeTimeBuilder)
>>> print one_month
relativedelta(months=+1)
>>> print two_months
relativedelta(months=+2)
>>> date(2003,1,27) + one_month
datetime.date(2003, 2, 27)
>>> date(2003,1,31) + one_month
datetime.date(2003, 2, 28)
>>> date(2003,1,31) + two_months
datetime.date(2003, 3, 31)

Alternatively, using the deprecated relative keyword:

>>> one_month = aniso8601.parse_duration('P1M', relative=True)
>>> two_months = aniso8601.parse_duration('P2M', relative=True)
>>> print one_month
relativedelta(months=+1)
>>> print two_months
relativedelta(months=+2)
>>> date(2003,1,27) + one_month
datetime.date(2003, 2, 27)
>>> date(2003,1,31) + one_month
datetime.date(2003, 2, 28)
>>> date(2003,1,31) + two_months
datetime.date(2003, 3, 31)

Fractional years and months do not make sense for relative durations. a RelativeValueError is raised when attempting to construct a duration with fractional month or year with the RelativeTimeBuilder:

>>> aniso8601.parse_duration('P2.1Y', builder=RelativeTimeBuilder)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "aniso8601/duration.py", line 39, in parse_duration
    return _parse_duration_prescribed(isodurationstr, builder)
  File "aniso8601/duration.py", line 84, in _parse_duration_prescribed
    return _parse_duration_prescribed_notime(durationstr, builder)
  File "aniso8601/duration.py", line 128, in _parse_duration_prescribed_notime
    PnW=weekstr, PnD=daystr)
  File "aniso8601/builder.py", line 564, in build_duration
    raise RelativeValueError('Fractional months and years are not '
aniso8601.exceptions.RelativeValueError: Fractional months and years are not defined for relative durations.

When attempting to construct a duration using a RelativeTimeBuilder without dateutil available, a RuntimeError is raised:

>>> aniso8601.parse_duration('P1M', builder=RelativeTimeBuilder)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/nielsenb/Jetfuse/aniso8601/test/lib/python2.7/site-packages/aniso8601/duration.py", line 39, in parse_duration
    return _parse_duration_prescribed(isodurationstr, builder)
  File "/home/nielsenb/Jetfuse/aniso8601/test/lib/python2.7/site-packages/aniso8601/duration.py", line 84, in _parse_duration_prescribed
    return _parse_duration_prescribed_notime(durationstr, builder)
  File "/home/nielsenb/Jetfuse/aniso8601/test/lib/python2.7/site-packages/aniso8601/duration.py", line 128, in _parse_duration_prescribed_notime
    PnW=weekstr, PnD=daystr)
  File "/home/nielsenb/Jetfuse/aniso8601/test/lib/python2.7/site-packages/aniso8601/builder.py", line 558, in build_duration
    raise RuntimeError('dateutil must be installed for '
RuntimeError: dateutil must be installed for relativedelta support.

Parsing intervals

To parse an interval specified by a start and end:

>>> import aniso8601
>>> aniso8601.parse_interval('2007-03-01T13:00:00/2008-05-11T15:30:00')
(datetime.datetime(2007, 3, 1, 13, 0), datetime.datetime(2008, 5, 11, 15, 30))

Intervals specified by a start time and a duration are supported:

>>> aniso8601.parse_interval('2007-03-01T13:00:00Z/P1Y2M10DT2H30M')
(datetime.datetime(2007, 3, 1, 13, 0, tzinfo=+0:00:00 UTC), datetime.datetime(2008, 5, 9, 15, 30, tzinfo=+0:00:00 UTC))

A duration can also be specified by a duration and end time:

>>> aniso8601.parse_interval('P1M/1981-04-05')
(datetime.date(1981, 4, 5), datetime.date(1981, 3, 6))

Notice that the result of the above parse is not in order from earliest to latest. If sorted intervals are required, simply use the sorted keyword as shown below:

>>> sorted(aniso8601.parse_interval('P1M/1981-04-05'))
[datetime.date(1981, 3, 6), datetime.date(1981, 4, 5)]

The end of an interval is given as a datetime when required to maintain the resolution specified by a duration, even if the duration start is given as a date:

>>> aniso8601.parse_interval('2014-11-12/PT4H54M6.5S')
(datetime.date(2014, 11, 12), datetime.datetime(2014, 11, 12, 4, 54, 6, 500000))

Repeating intervals are supported as well, and return a generator:

>>> aniso8601.parse_repeating_interval('R3/1981-04-05/P1D')
<generator object _date_generator at 0x7fd800d3b320>
>>> list(aniso8601.parse_repeating_interval('R3/1981-04-05/P1D'))
[datetime.date(1981, 4, 5), datetime.date(1981, 4, 6), datetime.date(1981, 4, 7)]

Repeating intervals are allowed to go in the reverse direction:

>>> list(aniso8601.parse_repeating_interval('R2/PT1H2M/1980-03-05T01:01:00'))
[datetime.datetime(1980, 3, 5, 1, 1), datetime.datetime(1980, 3, 4, 23, 59)]

Unbounded intervals are also allowed (Python 2):

>>> result = aniso8601.parse_repeating_interval('R/PT1H2M/1980-03-05T01:01:00')
>>> result.next()
datetime.datetime(1980, 3, 5, 1, 1)
>>> result.next()
datetime.datetime(1980, 3, 4, 23, 59)

or for Python 3:

>>> result = aniso8601.parse_repeating_interval('R/PT1H2M/1980-03-05T01:01:00')
>>> next(result)
datetime.datetime(1980, 3, 5, 1, 1)
>>> next(result)
datetime.datetime(1980, 3, 4, 23, 59)

Note that you should never try to convert a generator produced by an unbounded interval to a list:

>>> list(aniso8601.parse_repeating_interval('R/PT1H2M/1980-03-05T01:01:00'))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "aniso8601/builder.py", line 548, in _date_generator_unbounded
    currentdate += timedelta
OverflowError: date value out of range

The relative kwarg is deprecated and will be removed in aniso8601 5.0.0, use builder=RelativeTimeBuilder instead.

The above treat years as 365 days and months as 30 days. If calendar level accuracy is required, the provided RelativeTimeBuilder can be used if dateutil is installed:

>>> import aniso8601
>>> from aniso8601.builder import RelativeTimeBuilder
>>> aniso8601.parse_interval('2003-01-27/P1M', builder=RelativeTimeBuilder)
(datetime.date(2003, 1, 27), datetime.date(2003, 2, 27))
>>> aniso8601.parse_interval('2003-01-31/P1M', builder=RelativeTimeBuilder)
(datetime.date(2003, 1, 31), datetime.date(2003, 2, 28))
>>> aniso8601.parse_interval('P1Y/2001-02-28', builder=RelativeTimeBuilder)
(datetime.date(2001, 2, 28), datetime.date(2000, 2, 28))

Alternatively, using the deprecated relative keyword:

>>> aniso8601.parse_interval('2003-01-27/P1M', relative=True)
(datetime.date(2003, 1, 27), datetime.date(2003, 2, 27))
>>> aniso8601.parse_interval('2003-01-31/P1M', relative=True)
(datetime.date(2003, 1, 31), datetime.date(2003, 2, 28))
>>> aniso8601.parse_interval('P1Y/2001-02-28', relative=True)
(datetime.date(2001, 2, 28), datetime.date(2000, 2, 28)

Fractional years and months do not make sense for relative intervals. A RelativeValueError is raised when attempting to construct an interval with a fractional month or year with the RelativeTimeBuilder:

>>> aniso8601.parse_interval('P1.1Y/2001-02-28', builder=RelativeTimeBuilder)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "aniso8601/interval.py", line 50, in parse_interval
    intervaldelimiter, datetimedelimiter)
  File "aniso8601/interval.py", line 116, in _parse_interval
    return builder.build_interval(end=enddate, duration=duration)
  File "aniso8601/builder.py", line 393, in build_interval
    durationobject = cls._build_object(duration)
  File "aniso8601/builder.py", line 78, in _build_object
    TnS=parsetuple[6])
  File "aniso8601/builder.py", line 564, in build_duration
    raise RelativeValueError('Fractional months and years are not '
aniso8601.exceptions.RelativeValueError: Fractional months and years are not defined for relative durations.

When attempting to construct an interval using a RelativeTimeBuilder without dateutil available, a RuntimeError is raised:

>>> aniso8601.parse_interval('2003-01-27/P1M', builder=RelativeTimeBuilder)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/nielsenb/Jetfuse/aniso8601/test/lib/python2.7/site-packages/aniso8601/interval.py", line 50, in parse_interval
    intervaldelimiter, datetimedelimiter)
  File "/home/nielsenb/Jetfuse/aniso8601/test/lib/python2.7/site-packages/aniso8601/interval.py", line 135, in _parse_interval
    duration=duration)
  File "/home/nielsenb/Jetfuse/aniso8601/test/lib/python2.7/site-packages/aniso8601/builder.py", line 409, in build_interval
    durationobject = cls._build_object(duration)
  File "/home/nielsenb/Jetfuse/aniso8601/test/lib/python2.7/site-packages/aniso8601/builder.py", line 78, in _build_object
    TnS=parsetuple[6])
  File "/home/nielsenb/Jetfuse/aniso8601/test/lib/python2.7/site-packages/aniso8601/builder.py", line 558, in build_duration
    raise RuntimeError('dateutil must be installed for '
RuntimeError: dateutil must be installed for relativedelta support.

Date and time resolution

In some situations, it may be useful to figure out the resolution provided by an ISO 8601 date or time string. Two functions are provided for this purpose.

To get the resolution of a ISO 8601 time string:

>>> aniso8601.get_time_resolution('11:31:14') == aniso8601.resolution.TimeResolution.Seconds
True
>>> aniso8601.get_time_resolution('11:31') == aniso8601.resolution.TimeResolution.Minutes
True
>>> aniso8601.get_time_resolution('11') == aniso8601.resolution.TimeResolution.Hours
True

Similarly, for an ISO 8601 date string:

>>> aniso8601.get_date_resolution('1981-04-05') == aniso8601.resolution.DateResolution.Day
True
>>> aniso8601.get_date_resolution('1981-04') == aniso8601.resolution.DateResolution.Month
True
>>> aniso8601.get_date_resolution('1981') == aniso8601.resolution.DateResolution.Year
True

Builders

Builders can be used to change the output format of a parse operation. All parse functions have a builder keyword argument which accepts a builder class.

Three builders are included in the aniso8601.builder module: PythonTimeBuilder (the default), TupleBuilder which returns the parse result as a tuple of strings, and the RelativeTimeBuilder which allows for calendar level accuracy of duration and interval operations.

A NumPyTimeBuilder is available separately which supports parsing directly to NumPy datetime64 and timedelta64 types.

TupleBuilder

The TupleBuilder returns parse results as tuples of strings.

Datetimes

Parsing a datetime returns a tuple containing a date tuple as a collection of strings, a time tuple as a collection of strings, and the 'datetime' string. The date tuple contains the following parse components: (YYYY, MM, DD, Www, D, DDD, 'date'). The time tuple contains the following parse components (hh, mm, ss, tz, 'time'), where tz is a tuple with the following components (negative, Z, hh, mm, name, 'timezone') with negative and Z being booleans:

>>> import aniso8601
>>> from aniso8601.builder import TupleBuilder
>>> aniso8601.parse_datetime('1977-06-10T12:00:00', builder=TupleBuilder)
(('1977', '06', '10', None, None, None, 'date'), ('12', '00', '00', None, 'time'), 'datetime')
>>> aniso8601.parse_datetime('1979-06-05T08:00:00-08:00', builder=TupleBuilder)
(('1979', '06', '05', None, None, None, 'date'), ('08', '00', '00', (True, None, '08', '00', '-08:00', 'timezone'), 'time'), 'datetime')

Dates

Parsing a date returns a tuple containing the following parse components: (YYYY, MM, DD, Www, D, DDD, 'date'):

>>> import aniso8601
>>> from aniso8601.builder import TupleBuilder
>>> aniso8601.parse_date('1984-04-23', builder=TupleBuilder)
('1984', '04', '23', None, None, None, 'date')
>>> aniso8601.parse_date('1986-W38-1', builder=TupleBuilder)
('1986', None, None, '38', '1', None, 'date')
>>> aniso8601.parse_date('1988-132', builder=TupleBuilder)
('1988', None, None, None, None, '132', 'date')

Times

Parsing a time returns a tuple containing following parse components: (hh, mm, ss, tz, 'time'), where tz is a tuple with the following components (negative, Z, hh, mm, name, 'timezone') with negative and Z being booleans:

>>> import aniso8601
>>> from aniso8601.builder import TupleBuilder
>>> aniso8601.parse_time('11:31:14', builder=TupleBuilder)
('11', '31', '14', None, 'time')
>>> aniso8601.parse_time('171819Z', builder=TupleBuilder)
('17', '18', '19', (False, True, None, None, 'Z', 'timezone'), 'time')
>>> aniso8601.parse_time('17:18:19-02:30', builder=TupleBuilder)
('17', '18', '19', (True, None, '02', '30', '-02:30', 'timezone'), 'time')

Durations

Parsing a duration returns a tuple containing the following parse components: (PnY, PnM, PnW, PnD, TnH, TnM, TnS, 'duration'):

>>> import aniso8601
>>> from aniso8601.builder import TupleBuilder
>>> aniso8601.parse_duration('P1Y2M3DT4H54M6S', builder=TupleBuilder)
('1', '2', None, '3', '4', '54', '6', 'duration')
>>> aniso8601.parse_duration('P7W', builder=TupleBuilder)
(None, None, '7', None, None, None, None, 'duration')

Intervals

Parsing an interval returns a tuple containing the following parse components: (start, end, duration, 'interval'), start and end may both be datetime or date tuples, duration is a duration tuple:

>>> import aniso8601
>>> from aniso8601.builder import TupleBuilder
>>> aniso8601.parse_interval('2007-03-01T13:00:00/2008-05-11T15:30:00', builder=TupleBuilder)
((('2007', '03', '01', None, None, None, 'date'), ('13', '00', '00', None, 'time'), 'datetime'), (('2008', '05', '11', None, None, None, 'date'), ('15', '30', '00', None, 'time'), 'datetime'), None, 'interval')
>>> aniso8601.parse_interval('2007-03-01T13:00:00Z/P1Y2M10DT2H30M', builder=TupleBuilder)
((('2007', '03', '01', None, None, None, 'date'), ('13', '00', '00', (False, True, None, None, 'Z', 'timezone'), 'time'), 'datetime'), None, ('1', '2', None, '10', '2', '30', None, 'duration'), 'interval')
>>> aniso8601.parse_interval('P1M/1981-04-05', builder=TupleBuilder)
(None, ('1981', '04', '05', None, None, None, 'date'), (None, '1', None, None, None, None, None, 'duration'), 'interval')

A repeating interval returns a tuple containing the following parse components: (R, Rnn, interval, 'repeatinginterval') where R is a boolean, True for an unbounded interval, False otherwise.:

>>> aniso8601.parse_repeating_interval('R3/1981-04-05/P1D', builder=TupleBuilder)
(False, '3', (('1981', '04', '05', None, None, None, 'date'), None, (None, None, None, '1', None, None, None, 'duration'), 'interval'), 'repeatinginterval')
>>> aniso8601.parse_repeating_interval('R/PT1H2M/1980-03-05T01:01:00', builder=TupleBuilder)
(True, None, (None, (('1980', '03', '05', None, None, None, 'date'), ('01', '01', '00', None, 'time'), 'datetime'), (None, None, None, None, '1', '2', None, 'duration'), 'interval'), 'repeatinginterval')

RelativeTimeBuilder

The RelativeTimeBuilder uses python-dateutil (if installed) to add calendar level accuracy to duration and interval parses.

Datetimes

Same as PythonTimeBuilder.

Dates

Same as PythonTimeBuilder.

Times

Same as PythonTimeBuilder.

Durations

Parse will result in a relativedelta:

>>> import aniso8601
>>> from aniso8601.builder import RelativeTimeBuilder
>>> one_month = aniso8601.parse_duration('P1M', builder=RelativeTimeBuilder)
>>> two_months = aniso8601.parse_duration('P2M', builder=RelativeTimeBuilder)
>>> print one_month
relativedelta(months=+1)
>>> print two_months
relativedelta(months=+2)
>>> date(2003,1,27) + one_month
datetime.date(2003, 2, 27)
>>> date(2003,1,31) + one_month
datetime.date(2003, 2, 28)
>>> date(2003,1,31) + two_months
datetime.date(2003, 3, 31)

Since a relative fractional month or year is not logical, a RelativeValueError is raised when attempting to parse a duration with relative=True and fractional month or year:

>>> aniso8601.parse_duration('P2.1Y', builder=RelativeTimeBuilder)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "aniso8601/duration.py", line 39, in parse_duration
    return _parse_duration_prescribed(isodurationstr, builder)
  File "aniso8601/duration.py", line 84, in _parse_duration_prescribed
    return _parse_duration_prescribed_notime(durationstr, builder)
  File "aniso8601/duration.py", line 128, in _parse_duration_prescribed_notime
    PnW=weekstr, PnD=daystr)
  File "aniso8601/builder.py", line 564, in build_duration
    raise RelativeValueError('Fractional months and years are not '
aniso8601.exceptions.RelativeValueError: Fractional months and years are not defined for relative intervals.

If python-dateutil is not available, a RuntimeError is raised:

>>> aniso8601.parse_duration('P1M', builder=RelativeTimeBuilder)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "aniso8601/duration.py", line 39, in parse_duration
    return _parse_duration_prescribed(isodurationstr, builder)
  File "aniso8601/duration.py", line 84, in _parse_duration_prescribed
    return _parse_duration_prescribed_notime(durationstr, builder)
  File "aniso8601/duration.py", line 128, in _parse_duration_prescribed_notime
    PnW=weekstr, PnD=daystr)
  File "aniso8601/builder.py", line 558, in build_duration
    raise RuntimeError('dateutil must be installed for '
RuntimeError: dateutil must be installed for relativedelta support.

Intervals

Interval parse results will be calculated using a relativedelta internally, allowing for calendar level accuracy:

>>> import aniso8601
>>> from aniso8601.builder import RelativeTimeBuilder
>>> aniso8601.parse_interval('2003-01-27/P1M', builder=RelativeTimeBuilder)
(datetime.date(2003, 1, 27), datetime.date(2003, 2, 27))
>>> aniso8601.parse_interval('2003-01-31/P1M', builder=RelativeTimeBuilder)
(datetime.date(2003, 1, 31), datetime.date(2003, 2, 28))
>>> aniso8601.parse_interval('P1Y/2001-02-28', builder=RelativeTimeBuilder)
(datetime.date(2001, 2, 28), datetime.date(2000, 2, 28))

Fractional years and months do not make sense for relative intervals. A RelativeValueError is raised when attempting to parse an interval with relative=True and a fractional month or year:

>>> aniso8601.parse_interval('P1.1Y/2001-02-28', builder=RelativeTimeBuilder)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "aniso8601/interval.py", line 50, in parse_interval
    intervaldelimiter, datetimedelimiter)
  File "aniso8601/interval.py", line 116, in _parse_interval
    return builder.build_interval(end=enddate, duration=duration)
  File "aniso8601/builder.py", line 393, in build_interval
    durationobject = cls._build_object(duration)
  File "aniso8601/builder.py", line 78, in _build_object
    TnS=parsetuple[6])
  File "aniso8601/builder.py", line 564, in build_duration
    raise RelativeValueError('Fractional months and years are not '
aniso8601.exceptions.RelativeValueError: Fractional months and years are not defined for relative intervals.

If python-dateutil is not available, a RuntimeError is raised:

>>> aniso8601.parse_interval('2003-01-27/P1M', builder=RelativeTimeBuilder)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "aniso8601/interval.py", line 50, in parse_interval
    intervaldelimiter, datetimedelimiter)
  File "aniso8601/interval.py", line 135, in _parse_interval
    duration=duration)
  File "aniso8601/builder.py", line 409, in build_interval
    durationobject = cls._build_object(duration)
  File "aniso8601/builder.py", line 78, in _build_object
    TnS=parsetuple[6])
  File "aniso8601/builder.py", line 558, in build_duration
    raise RuntimeError('dateutil must be installed for '
RuntimeError: dateutil must be installed for relativedelta support.

Development

Setup

It is recommended to develop using a virtualenv.

The tests require the dev and relative features to be enabled, install the necessary dependencies using pip:

$ pip install .[dev,relative]

Tests

To run the unit tests, navigate to the source directory and run the tests for the python version being worked on (python2, python3):

$ python2 -m unittest discover aniso8601/tests/

or:

$ python3 -m unittest discover aniso8601/tests/

Contributing

aniso8601 is an open source project hosted on Bitbucket.

Any and all bugs are welcome on our issue tracker. Of particular interest are valid ISO 8601 strings that don't parse, or invalid ones that do. At a minimum, bug reports should include an example of the misbehaving string, as well as the expected result. Of course patches containing unit tests (or fixed bugs) are welcome!