Fixed #22598 -- Allowed make_aware() to work with ambiguous datetime

This commit is contained in:
Josh Smeaton 2015-03-31 16:58:37 +11:00 committed by Tim Graham
parent 269a5dbdd3
commit 143255c8bb
4 changed files with 59 additions and 5 deletions

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@ -347,7 +347,7 @@ def is_naive(value):
return value.tzinfo is None or value.tzinfo.utcoffset(value) is None
def make_aware(value, timezone=None):
def make_aware(value, timezone=None, is_dst=None):
"""
Makes a naive datetime.datetime in a given time zone aware.
"""
@ -355,7 +355,7 @@ def make_aware(value, timezone=None):
timezone = get_current_timezone()
if hasattr(timezone, 'localize'):
# This method is available for pytz time zones.
return timezone.localize(value, is_dst=None)
return timezone.localize(value, is_dst=is_dst)
else:
# Check that we won't overwrite the timezone of an aware datetime.
if is_aware(value):

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@ -947,20 +947,37 @@ appropriate entities.
Returns ``True`` if ``value`` is naive, ``False`` if it is aware. This
function assumes that ``value`` is a :class:`~datetime.datetime`.
.. function:: make_aware(value, timezone=None)
.. function:: make_aware(value, timezone=None, is_dst=None)
Returns an aware :class:`~datetime.datetime` that represents the same
point in time as ``value`` in ``timezone``, ``value`` being a naive
:class:`~datetime.datetime`. If ``timezone`` is set to ``None``, it
defaults to the :ref:`current time zone <default-current-time-zone>`.
This function can raise an exception if ``value`` doesn't exist or is
ambiguous because of DST transitions.
When pytz_ is installed, the exception ``pytz.AmbiguousTimeError``
will be raised if you try to make ``value`` aware during a DST transition
where the same time occurs twice (when reverting from DST). Setting
``is_dst`` to ``True`` or ``False`` will avoid the exception by choosing if
the time is pre-transition or post-transition respectively.
When pytz_ is installed, the exception ``pytz.NonExistentTimeError``
will be raised if you try to make ``value`` aware during a DST transition
such that the time never occurred (when entering into DST). Setting
``is_dst`` to ``True`` or ``False`` will avoid the exception by moving the
hour backwards or forwards by 1 respectively. For example, ``is_dst=True``
would change a non-existent time of 2:30 to 1:30 and ``is_dst=False``
would change the time to 3:30.
``is_dst`` has no effect when ``pytz`` is not installed.
.. versionchanged:: 1.8
In older versions of Django, ``timezone`` was a required argument.
.. versionchanged:: 1.9
The ``is_dst`` argument was added.
.. function:: make_naive(value, timezone=None)
Returns an naive :class:`~datetime.datetime` that represents in

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@ -159,6 +159,9 @@ Internationalization
* The :func:`django.views.i18n.javascript_catalog` view now works correctly
if used multiple times with different configurations on the same page.
* The :func:`django.utils.timezone.make_aware` function gained an ``is_dst``
argument to help resolve ambiguous times during DST transitions.
Management Commands
^^^^^^^^^^^^^^^^^^^

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@ -155,3 +155,37 @@ class TimezoneTests(unittest.TestCase):
datetime.datetime(2011, 9, 1, 12, 20, 30))
with self.assertRaises(ValueError):
timezone.make_naive(datetime.datetime(2011, 9, 1, 12, 20, 30), CET)
@unittest.skipIf(pytz is None, "this test requires pytz")
def test_make_aware_pytz_ambiguous(self):
# 2:30 happens twice, once before DST ends and once after
ambiguous = datetime.datetime(2015, 10, 25, 2, 30)
with self.assertRaises(pytz.AmbiguousTimeError):
timezone.make_aware(ambiguous, timezone=CET)
std = timezone.make_aware(ambiguous, timezone=CET, is_dst=False)
dst = timezone.make_aware(ambiguous, timezone=CET, is_dst=True)
self.assertEqual(std - dst, datetime.timedelta(hours=1))
self.assertEqual(std.tzinfo.utcoffset(std), datetime.timedelta(hours=1))
self.assertEqual(dst.tzinfo.utcoffset(dst), datetime.timedelta(hours=2))
@unittest.skipIf(pytz is None, "this test requires pytz")
def test_make_aware_pytz_non_existent(self):
# 2:30 never happened due to DST
non_existent = datetime.datetime(2015, 3, 29, 2, 30)
with self.assertRaises(pytz.NonExistentTimeError):
timezone.make_aware(non_existent, timezone=CET)
std = timezone.make_aware(non_existent, timezone=CET, is_dst=False)
dst = timezone.make_aware(non_existent, timezone=CET, is_dst=True)
self.assertEqual(std - dst, datetime.timedelta(hours=1))
self.assertEqual(std.tzinfo.utcoffset(std), datetime.timedelta(hours=1))
self.assertEqual(dst.tzinfo.utcoffset(dst), datetime.timedelta(hours=2))
# round trip to UTC then back to CET
std = timezone.localtime(timezone.localtime(std, timezone.UTC()), CET)
dst = timezone.localtime(timezone.localtime(dst, timezone.UTC()), CET)
self.assertEqual((std.hour, std.minute), (3, 30))
self.assertEqual((dst.hour, dst.minute), (1, 30))