Fixed #25774 -- Refactor datetime expressions into public API

1 files changed, 694 insertions, 0 deletions

diff --git a/tests/db_functions/test_datetime.py b/tests/db_functions/test_datetime.py
new file mode 100644
index 0000000000..011db8bb88
--- /dev/null
+++ b/tests/db_functions/test_datetime.py
@@ -0,0 +1,694 @@
+from __future__ import unicode_literals
+
+from datetime import datetime
+from unittest import skipIf
+
+from django.conf import settings
+from django.db import connection
+from django.db.models import DateField, DateTimeField, IntegerField
+from django.db.models.functions import (
+    Extract, ExtractDay, ExtractHour, ExtractMinute, ExtractMonth,
+    ExtractSecond, ExtractWeekDay, ExtractYear, Trunc, TruncDate, TruncDay,
+    TruncHour, TruncMinute, TruncMonth, TruncSecond, TruncYear,
+)
+from django.test import TestCase, override_settings
+from django.utils import timezone
+
+from .models import DTModel
+
+try:
+    import pytz
+except ImportError:
+    pytz = None
+
+
+def microsecond_support(value):
+    return value if connection.features.supports_microsecond_precision else value.replace(microsecond=0)
+
+
+def truncate_to(value, kind, tzinfo=None):
+    # Convert to target timezone before truncation
+    if tzinfo is not None:
+        value = value.astimezone(tzinfo)
+
+    def truncate(value, kind):
+        if kind == 'second':
+            return value.replace(microsecond=0)
+        if kind == 'minute':
+            return value.replace(second=0, microsecond=0)
+        if kind == 'hour':
+            return value.replace(minute=0, second=0, microsecond=0)
+        if kind == 'day':
+            if isinstance(value, datetime):
+                return value.replace(hour=0, minute=0, second=0, microsecond=0)
+            return value
+        if kind == 'month':
+            if isinstance(value, datetime):
+                return value.replace(day=1, hour=0, minute=0, second=0, microsecond=0)
+            return value.replace(day=1)
+        # otherwise, truncate to year
+        if isinstance(value, datetime):
+            return value.replace(month=1, day=1, hour=0, minute=0, second=0, microsecond=0)
+        return value.replace(month=1, day=1)
+
+    value = truncate(value, kind)
+    if tzinfo is not None:
+        # If there was a daylight saving transition, then reset the timezone.
+        value = timezone.make_aware(value.replace(tzinfo=None), tzinfo)
+    return value
+
+
+@override_settings(USE_TZ=False)
+class DateFunctionTests(TestCase):
+
+    def create_model(self, start_datetime, end_datetime):
+        return DTModel.objects.create(
+            name=start_datetime.isoformat(),
+            start_datetime=start_datetime, end_datetime=end_datetime,
+            start_date=start_datetime.date(), end_date=end_datetime.date(),
+            start_time=start_datetime.time(), end_time=end_datetime.time(),
+            duration=(end_datetime - start_datetime),
+        )
+
+    def test_extract_year_exact_lookup(self):
+        """
+        Extract year uses a BETWEEN filter to compare the year to allow indexes
+        to be used.
+        """
+        start_datetime = datetime(2015, 6, 15, 14, 10)
+        end_datetime = datetime(2016, 6, 15, 14, 10)
+        if settings.USE_TZ:
+            start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+            end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        self.create_model(end_datetime, start_datetime)
+
+        qs = DTModel.objects.filter(start_datetime__year__exact=2015)
+        self.assertEqual(qs.count(), 1)
+        query_string = str(qs.query).lower()
+        self.assertEqual(query_string.count(' between '), 1)
+        self.assertEqual(query_string.count('extract'), 0)
+
+        # exact is implied and should be the same
+        qs = DTModel.objects.filter(start_datetime__year=2015)
+        self.assertEqual(qs.count(), 1)
+        query_string = str(qs.query).lower()
+        self.assertEqual(query_string.count(' between '), 1)
+        self.assertEqual(query_string.count('extract'), 0)
+
+        # date and datetime fields should behave the same
+        qs = DTModel.objects.filter(start_date__year=2015)
+        self.assertEqual(qs.count(), 1)
+        query_string = str(qs.query).lower()
+        self.assertEqual(query_string.count(' between '), 1)
+        self.assertEqual(query_string.count('extract'), 0)
+
+    def test_extract_year_greaterthan_lookup(self):
+        start_datetime = datetime(2015, 6, 15, 14, 10)
+        end_datetime = datetime(2016, 6, 15, 14, 10)
+        if settings.USE_TZ:
+            start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+            end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        self.create_model(end_datetime, start_datetime)
+
+        qs = DTModel.objects.filter(start_datetime__year__gt=2015)
+        self.assertEqual(qs.count(), 1)
+        self.assertEqual(str(qs.query).lower().count('extract'), 0)
+        qs = DTModel.objects.filter(start_datetime__year__gte=2015)
+        self.assertEqual(qs.count(), 2)
+        self.assertEqual(str(qs.query).lower().count('extract'), 0)
+
+    def test_extract_year_lessthan_lookup(self):
+        start_datetime = datetime(2015, 6, 15, 14, 10)
+        end_datetime = datetime(2016, 6, 15, 14, 10)
+        if settings.USE_TZ:
+            start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+            end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        self.create_model(end_datetime, start_datetime)
+
+        qs = DTModel.objects.filter(start_datetime__year__lt=2016)
+        self.assertEqual(qs.count(), 1)
+        self.assertEqual(str(qs.query).count('extract'), 0)
+        qs = DTModel.objects.filter(start_datetime__year__lte=2016)
+        self.assertEqual(qs.count(), 2)
+        self.assertEqual(str(qs.query).count('extract'), 0)
+
+    def test_extract_func(self):
+        start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
+        end_datetime = microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123))
+        if settings.USE_TZ:
+            start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+            end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        self.create_model(end_datetime, start_datetime)
+
+        with self.assertRaisesMessage(ValueError, 'lookup_name must be provided'):
+            Extract('start_datetime')
+
+        msg = 'Extract input expression must be DateField, DateTimeField, or TimeField.'
+        with self.assertRaisesMessage(ValueError, msg):
+            list(DTModel.objects.annotate(extracted=Extract('name', 'hour')))
+
+        with self.assertRaisesMessage(
+                ValueError, "Cannot extract time component 'second' from DateField 'start_date'."):
+            list(DTModel.objects.annotate(extracted=Extract('start_date', 'second')))
+
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=Extract('start_datetime', 'year')).order_by('start_datetime'),
+            [(start_datetime, start_datetime.year), (end_datetime, end_datetime.year)],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=Extract('start_datetime', 'month')).order_by('start_datetime'),
+            [(start_datetime, start_datetime.month), (end_datetime, end_datetime.month)],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=Extract('start_datetime', 'day')).order_by('start_datetime'),
+            [(start_datetime, start_datetime.day), (end_datetime, end_datetime.day)],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=Extract('start_datetime', 'week_day')).order_by('start_datetime'),
+            [
+                (start_datetime, (start_datetime.isoweekday() % 7) + 1),
+                (end_datetime, (end_datetime.isoweekday() % 7) + 1)
+            ],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=Extract('start_datetime', 'hour')).order_by('start_datetime'),
+            [(start_datetime, start_datetime.hour), (end_datetime, end_datetime.hour)],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=Extract('start_datetime', 'minute')).order_by('start_datetime'),
+            [(start_datetime, start_datetime.minute), (end_datetime, end_datetime.minute)],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=Extract('start_datetime', 'second')).order_by('start_datetime'),
+            [(start_datetime, start_datetime.second), (end_datetime, end_datetime.second)],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertEqual(DTModel.objects.filter(start_datetime__year=Extract('start_datetime', 'year')).count(), 2)
+        self.assertEqual(DTModel.objects.filter(start_datetime__hour=Extract('start_datetime', 'hour')).count(), 2)
+        self.assertEqual(DTModel.objects.filter(start_date__month=Extract('start_date', 'month')).count(), 2)
+        self.assertEqual(DTModel.objects.filter(start_time__hour=Extract('start_time', 'hour')).count(), 2)
+
+    def test_extract_year_func(self):
+        start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
+        end_datetime = microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123))
+        if settings.USE_TZ:
+            start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+            end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        self.create_model(end_datetime, start_datetime)
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=ExtractYear('start_datetime')).order_by('start_datetime'),
+            [(start_datetime, start_datetime.year), (end_datetime, end_datetime.year)],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=ExtractYear('start_date')).order_by('start_datetime'),
+            [(start_datetime, start_datetime.year), (end_datetime, end_datetime.year)],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertEqual(DTModel.objects.filter(start_datetime__year=ExtractYear('start_datetime')).count(), 2)
+
+    def test_extract_month_func(self):
+        start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
+        end_datetime = microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123))
+        if settings.USE_TZ:
+            start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+            end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        self.create_model(end_datetime, start_datetime)
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=ExtractMonth('start_datetime')).order_by('start_datetime'),
+            [(start_datetime, start_datetime.month), (end_datetime, end_datetime.month)],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=ExtractMonth('start_date')).order_by('start_datetime'),
+            [(start_datetime, start_datetime.month), (end_datetime, end_datetime.month)],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertEqual(DTModel.objects.filter(start_datetime__month=ExtractMonth('start_datetime')).count(), 2)
+
+    def test_extract_day_func(self):
+        start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
+        end_datetime = microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123))
+        if settings.USE_TZ:
+            start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+            end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        self.create_model(end_datetime, start_datetime)
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=ExtractDay('start_datetime')).order_by('start_datetime'),
+            [(start_datetime, start_datetime.day), (end_datetime, end_datetime.day)],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=ExtractDay('start_date')).order_by('start_datetime'),
+            [(start_datetime, start_datetime.day), (end_datetime, end_datetime.day)],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertEqual(DTModel.objects.filter(start_datetime__day=ExtractDay('start_datetime')).count(), 2)
+
+    def test_extract_weekday_func(self):
+        start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
+        end_datetime = microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123))
+        if settings.USE_TZ:
+            start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+            end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        self.create_model(end_datetime, start_datetime)
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=ExtractWeekDay('start_datetime')).order_by('start_datetime'),
+            [
+                (start_datetime, (start_datetime.isoweekday() % 7) + 1),
+                (end_datetime, (end_datetime.isoweekday() % 7) + 1),
+            ],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=ExtractWeekDay('start_date')).order_by('start_datetime'),
+            [
+                (start_datetime, (start_datetime.isoweekday() % 7) + 1),
+                (end_datetime, (end_datetime.isoweekday() % 7) + 1),
+            ],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertEqual(DTModel.objects.filter(start_datetime__week_day=ExtractWeekDay('start_datetime')).count(), 2)
+
+    def test_extract_hour_func(self):
+        start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
+        end_datetime = microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123))
+        if settings.USE_TZ:
+            start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+            end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        self.create_model(end_datetime, start_datetime)
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=ExtractHour('start_datetime')).order_by('start_datetime'),
+            [(start_datetime, start_datetime.hour), (end_datetime, end_datetime.hour)],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=ExtractHour('start_time')).order_by('start_datetime'),
+            [(start_datetime, start_datetime.hour), (end_datetime, end_datetime.hour)],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertEqual(DTModel.objects.filter(start_datetime__hour=ExtractHour('start_datetime')).count(), 2)
+
+    def test_extract_minute_func(self):
+        start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
+        end_datetime = microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123))
+        if settings.USE_TZ:
+            start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+            end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        self.create_model(end_datetime, start_datetime)
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=ExtractMinute('start_datetime')).order_by('start_datetime'),
+            [(start_datetime, start_datetime.minute), (end_datetime, end_datetime.minute)],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=ExtractMinute('start_time')).order_by('start_datetime'),
+            [(start_datetime, start_datetime.minute), (end_datetime, end_datetime.minute)],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertEqual(DTModel.objects.filter(start_datetime__minute=ExtractMinute('start_datetime')).count(), 2)
+
+    def test_extract_second_func(self):
+        start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
+        end_datetime = microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123))
+        if settings.USE_TZ:
+            start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+            end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        self.create_model(end_datetime, start_datetime)
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=ExtractSecond('start_datetime')).order_by('start_datetime'),
+            [(start_datetime, start_datetime.second), (end_datetime, end_datetime.second)],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=ExtractSecond('start_time')).order_by('start_datetime'),
+            [(start_datetime, start_datetime.second), (end_datetime, end_datetime.second)],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertEqual(DTModel.objects.filter(start_datetime__second=ExtractSecond('start_datetime')).count(), 2)
+
+    def test_trunc_func(self):
+        start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
+        end_datetime = microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123))
+        if settings.USE_TZ:
+            start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+            end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        self.create_model(end_datetime, start_datetime)
+
+        with self.assertRaisesMessage(ValueError, 'output_field must be either DateField or DateTimeField'):
+            list(DTModel.objects.annotate(truncated=Trunc('start_datetime', 'year', output_field=IntegerField())))
+
+        with self.assertRaisesMessage(AssertionError, "'name' isn't a DateField or DateTimeField."):
+            list(DTModel.objects.annotate(truncated=Trunc('name', 'year', output_field=DateTimeField())))
+
+        with self.assertRaisesMessage(ValueError, "Cannot truncate DateField 'start_date' to DateTimeField"):
+            list(DTModel.objects.annotate(truncated=Trunc('start_date', 'second')))
+
+        with self.assertRaisesMessage(ValueError, "Cannot truncate DateField 'start_date' to DateTimeField"):
+            list(DTModel.objects.annotate(truncated=Trunc('start_date', 'month', output_field=DateTimeField())))
+
+        def test_datetime_kind(kind):
+            self.assertQuerysetEqual(
+                DTModel.objects.annotate(
+                    truncated=Trunc('start_datetime', kind, output_field=DateTimeField())
+                ).order_by('start_datetime'),
+                [
+                    (start_datetime, truncate_to(start_datetime, kind)),
+                    (end_datetime, truncate_to(end_datetime, kind))
+                ],
+                lambda m: (m.start_datetime, m.truncated)
+            )
+
+        def test_date_kind(kind):
+            self.assertQuerysetEqual(
+                DTModel.objects.annotate(
+                    truncated=Trunc('start_date', kind, output_field=DateField())
+                ).order_by('start_datetime'),
+                [
+                    (start_datetime, truncate_to(start_datetime.date(), kind)),
+                    (end_datetime, truncate_to(end_datetime.date(), kind))
+                ],
+                lambda m: (m.start_datetime, m.truncated)
+            )
+
+        test_date_kind('year')
+        test_date_kind('month')
+        test_date_kind('day')
+        test_datetime_kind('year')
+        test_datetime_kind('month')
+        test_datetime_kind('day')
+        test_datetime_kind('hour')
+        test_datetime_kind('minute')
+        test_datetime_kind('second')
+
+        qs = DTModel.objects.filter(start_datetime__date=Trunc('start_datetime', 'day', output_field=DateField()))
+        self.assertEqual(qs.count(), 2)
+
+    def test_trunc_year_func(self):
+        start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
+        end_datetime = truncate_to(microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123)), 'year')
+        if settings.USE_TZ:
+            start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+            end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        self.create_model(end_datetime, start_datetime)
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=TruncYear('start_datetime')).order_by('start_datetime'),
+            [
+                (start_datetime, truncate_to(start_datetime, 'year')),
+                (end_datetime, truncate_to(end_datetime, 'year')),
+            ],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=TruncYear('start_date')).order_by('start_datetime'),
+            [
+                (start_datetime, truncate_to(start_datetime.date(), 'year')),
+                (end_datetime, truncate_to(end_datetime.date(), 'year')),
+            ],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertEqual(DTModel.objects.filter(start_datetime=TruncYear('start_datetime')).count(), 1)
+
+    def test_trunc_month_func(self):
+        start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
+        end_datetime = truncate_to(microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123)), 'month')
+        if settings.USE_TZ:
+            start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+            end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        self.create_model(end_datetime, start_datetime)
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=TruncMonth('start_datetime')).order_by('start_datetime'),
+            [
+                (start_datetime, truncate_to(start_datetime, 'month')),
+                (end_datetime, truncate_to(end_datetime, 'month')),
+            ],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=TruncMonth('start_date')).order_by('start_datetime'),
+            [
+                (start_datetime, truncate_to(start_datetime.date(), 'month')),
+                (end_datetime, truncate_to(end_datetime.date(), 'month')),
+            ],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertEqual(DTModel.objects.filter(start_datetime=TruncMonth('start_datetime')).count(), 1)
+
+    def test_trunc_date_func(self):
+        start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
+        end_datetime = microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123))
+        if settings.USE_TZ:
+            start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+            end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        self.create_model(end_datetime, start_datetime)
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=TruncDate('start_datetime')).order_by('start_datetime'),
+            [
+                (start_datetime, start_datetime.date()),
+                (end_datetime, end_datetime.date()),
+            ],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertEqual(DTModel.objects.filter(start_datetime__date=TruncDate('start_datetime')).count(), 2)
+
+    def test_trunc_day_func(self):
+        start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
+        end_datetime = truncate_to(microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123)), 'day')
+        if settings.USE_TZ:
+            start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+            end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        self.create_model(end_datetime, start_datetime)
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=TruncDay('start_datetime')).order_by('start_datetime'),
+            [
+                (start_datetime, truncate_to(start_datetime, 'day')),
+                (end_datetime, truncate_to(end_datetime, 'day')),
+            ],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertEqual(DTModel.objects.filter(start_datetime=TruncDay('start_datetime')).count(), 1)
+
+    def test_trunc_hour_func(self):
+        start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
+        end_datetime = truncate_to(microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123)), 'hour')
+        if settings.USE_TZ:
+            start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+            end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        self.create_model(end_datetime, start_datetime)
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=TruncHour('start_datetime')).order_by('start_datetime'),
+            [
+                (start_datetime, truncate_to(start_datetime, 'hour')),
+                (end_datetime, truncate_to(end_datetime, 'hour')),
+            ],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertEqual(DTModel.objects.filter(start_datetime=TruncHour('start_datetime')).count(), 1)
+
+        with self.assertRaisesMessage(ValueError, "Cannot truncate DateField 'start_date' to DateTimeField"):
+            list(DTModel.objects.annotate(truncated=TruncHour('start_date')))
+
+        with self.assertRaisesMessage(ValueError, "Cannot truncate DateField 'start_date' to DateTimeField"):
+            list(DTModel.objects.annotate(truncated=TruncHour('start_date', output_field=DateField())))
+
+    def test_trunc_minute_func(self):
+        start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
+        end_datetime = truncate_to(microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123)), 'minute')
+        if settings.USE_TZ:
+            start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+            end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        self.create_model(end_datetime, start_datetime)
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=TruncMinute('start_datetime')).order_by('start_datetime'),
+            [
+                (start_datetime, truncate_to(start_datetime, 'minute')),
+                (end_datetime, truncate_to(end_datetime, 'minute')),
+            ],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+        self.assertEqual(DTModel.objects.filter(start_datetime=TruncMinute('start_datetime')).count(), 1)
+
+        with self.assertRaisesMessage(ValueError, "Cannot truncate DateField 'start_date' to DateTimeField"):
+            list(DTModel.objects.annotate(truncated=TruncMinute('start_date')))
+
+        with self.assertRaisesMessage(ValueError, "Cannot truncate DateField 'start_date' to DateTimeField"):
+            list(DTModel.objects.annotate(truncated=TruncMinute('start_date', output_field=DateField())))
+
+    def test_trunc_second_func(self):
+        start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
+        end_datetime = truncate_to(microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123)), 'second')
+        if settings.USE_TZ:
+            start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+            end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        self.create_model(end_datetime, start_datetime)
+        self.assertQuerysetEqual(
+            DTModel.objects.annotate(extracted=TruncSecond('start_datetime')).order_by('start_datetime'),
+            [
+                (start_datetime, truncate_to(start_datetime, 'second')),
+                (end_datetime, truncate_to(end_datetime, 'second'))
+            ],
+            lambda m: (m.start_datetime, m.extracted)
+        )
+
+        result = 1 if connection.features.supports_microsecond_precision else 2
+        self.assertEqual(DTModel.objects.filter(start_datetime=TruncSecond('start_datetime')).count(), result)
+
+        with self.assertRaisesMessage(ValueError, "Cannot truncate DateField 'start_date' to DateTimeField"):
+            list(DTModel.objects.annotate(truncated=TruncSecond('start_date')))
+
+        with self.assertRaisesMessage(ValueError, "Cannot truncate DateField 'start_date' to DateTimeField"):
+            list(DTModel.objects.annotate(truncated=TruncSecond('start_date', output_field=DateField())))
+
+
+@skipIf(pytz is None, "this test requires pytz")
+@override_settings(USE_TZ=True, TIME_ZONE='UTC')
+class DateFunctionWithTimeZoneTests(DateFunctionTests):
+
+    def test_extract_func_with_timezone(self):
+        start_datetime = microsecond_support(datetime(2015, 6, 15, 23, 30, 1, 321))
+        end_datetime = microsecond_support(datetime(2015, 6, 16, 13, 11, 27, 123))
+        start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+        end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        melb = pytz.timezone('Australia/Melbourne')
+
+        qs = DTModel.objects.annotate(
+            day=Extract('start_datetime', 'day'),
+            day_melb=Extract('start_datetime', 'day', tzinfo=melb),
+            weekday=ExtractWeekDay('start_datetime'),
+            weekday_melb=ExtractWeekDay('start_datetime', tzinfo=melb),
+            hour=ExtractHour('start_datetime'),
+            hour_melb=ExtractHour('start_datetime', tzinfo=melb),
+        ).order_by('start_datetime')
+
+        utc_model = qs.get()
+        self.assertEqual(utc_model.day, 15)
+        self.assertEqual(utc_model.day_melb, 16)
+        self.assertEqual(utc_model.weekday, 2)
+        self.assertEqual(utc_model.weekday_melb, 3)
+        self.assertEqual(utc_model.hour, 23)
+        self.assertEqual(utc_model.hour_melb, 9)
+
+        with timezone.override(melb):
+            melb_model = qs.get()
+
+        self.assertEqual(melb_model.day, 16)
+        self.assertEqual(melb_model.day_melb, 16)
+        self.assertEqual(melb_model.weekday, 3)
+        self.assertEqual(melb_model.weekday_melb, 3)
+        self.assertEqual(melb_model.hour, 9)
+        self.assertEqual(melb_model.hour_melb, 9)
+
+    def test_extract_func_explicit_timezone_priority(self):
+        start_datetime = microsecond_support(datetime(2015, 6, 15, 23, 30, 1, 321))
+        end_datetime = microsecond_support(datetime(2015, 6, 16, 13, 11, 27, 123))
+        start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+        end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        melb = pytz.timezone('Australia/Melbourne')
+
+        with timezone.override(melb):
+            model = DTModel.objects.annotate(
+                day_melb=Extract('start_datetime', 'day'),
+                day_utc=Extract('start_datetime', 'day', tzinfo=timezone.utc),
+            ).order_by('start_datetime').get()
+            self.assertEqual(model.day_melb, 16)
+            self.assertEqual(model.day_utc, 15)
+
+    def test_trunc_timezone_applied_before_truncation(self):
+        start_datetime = microsecond_support(datetime(2016, 1, 1, 1, 30, 50, 321))
+        end_datetime = microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123))
+        start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+        end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+
+        melb = pytz.timezone('Australia/Melbourne')
+        pacific = pytz.timezone('US/Pacific')
+
+        model = DTModel.objects.annotate(
+            melb_year=TruncYear('start_datetime', tzinfo=melb),
+            pacific_year=TruncYear('start_datetime', tzinfo=pacific),
+        ).order_by('start_datetime').get()
+
+        self.assertEqual(model.start_datetime, start_datetime)
+        self.assertEqual(model.melb_year, truncate_to(start_datetime, 'year', melb))
+        self.assertEqual(model.pacific_year, truncate_to(start_datetime, 'year', pacific))
+        self.assertEqual(model.start_datetime.year, 2016)
+        self.assertEqual(model.melb_year.year, 2016)
+        self.assertEqual(model.pacific_year.year, 2015)
+
+    def test_trunc_func_with_timezone(self):
+        """
+        If the truncated datetime transitions to a different offset (daylight
+        saving) then the returned value will have that new timezone/offset.
+        """
+        start_datetime = microsecond_support(datetime(2015, 6, 15, 14, 30, 50, 321))
+        end_datetime = microsecond_support(datetime(2016, 6, 15, 14, 10, 50, 123))
+        start_datetime = timezone.make_aware(start_datetime, is_dst=False)
+        end_datetime = timezone.make_aware(end_datetime, is_dst=False)
+        self.create_model(start_datetime, end_datetime)
+        self.create_model(end_datetime, start_datetime)
+
+        melb = pytz.timezone('Australia/Melbourne')
+
+        def test_datetime_kind(kind, tzinfo=melb):
+            self.assertQuerysetEqual(
+                DTModel.objects.annotate(
+                    truncated=Trunc('start_datetime', kind, output_field=DateTimeField(), tzinfo=melb)
+                ).order_by('start_datetime'),
+                [
+                    (start_datetime, truncate_to(start_datetime.astimezone(melb), kind, melb)),
+                    (end_datetime, truncate_to(end_datetime.astimezone(melb), kind, melb))
+                ],
+                lambda m: (m.start_datetime, m.truncated)
+            )
+
+        def test_date_kind(kind, tzinfo=melb):
+            self.assertQuerysetEqual(
+                DTModel.objects.annotate(
+                    truncated=Trunc('start_date', kind, output_field=DateField(), tzinfo=melb)
+                ).order_by('start_datetime'),
+                [
+                    (start_datetime, truncate_to(start_datetime.date(), kind)),
+                    (end_datetime, truncate_to(end_datetime.date(), kind))
+                ],
+                lambda m: (m.start_datetime, m.truncated)
+            )
+
+        test_date_kind('year')
+        test_date_kind('month')
+        test_date_kind('day')
+        test_datetime_kind('year')
+        test_datetime_kind('month')
+        test_datetime_kind('day')
+        test_datetime_kind('hour')
+        test_datetime_kind('minute')
+        test_datetime_kind('second')
+
+        qs = DTModel.objects.filter(start_datetime__date=Trunc('start_datetime', 'day', output_field=DateField()))
+        self.assertEqual(qs.count(), 2)