Fixed #17294 -- Supported nullable DateTimeFields when time zone support is...

    def get_prep_value(self, value):

        value = self.to_python(value)

        if settings.USE_TZ and timezone.is_naive(value):

        if value is not None and settings.USE_TZ and timezone.is_naive(value):

            # For backwards compatibility, interpret naive datetimes in local

            # time. This won't work during DST change, but we can't do much

            # about it, so we let the exceptions percolate up the call stack.

    else:

        return datetime.now()

# By design, these four functions don't perform any checks on their arguments.

# The caller should ensure that they don't receive an invalid value like None.

def is_aware(value):

    """

    Determines if a given datetime.datetime is aware.

class Event(models.Model):

    dt = models.DateTimeField()

class MaybeEvent(models.Model):

    dt = models.DateTimeField(blank=True, null=True)

class Timestamp(models.Model):

    created = models.DateTimeField(auto_now_add=True)

    updated = models.DateTimeField(auto_now=True)

from django.utils.unittest import skipIf

from .forms import EventForm, EventSplitForm, EventModelForm

from .models import Event, Timestamp

from .models import Event, MaybeEvent, Timestamp

# These tests use the EAT (Eastern Africa Time) and ICT (Indochina Time)

                 datetime.datetime(2011, 1, 1, tzinfo=UTC)],

                transform=lambda d: d)

    def test_null_datetime(self):

        # Regression for #17294

        e = MaybeEvent.objects.create()

        self.assertEqual(e.dt, None)

NewDatabaseTests = override_settings(USE_TZ=True)(NewDatabaseTests)