django/tests/db_functions/comparison/test_cast.py

import datetime
import decimal
import unittest

from django.db import connection, models
from django.db.models.functions import Cast
from django.test import TestCase, ignore_warnings, skipUnlessDBFeature
from django.test.utils import CaptureQueriesContext

from ..models import Author, DTModel, Fan, FloatModel


class CastTests(TestCase):
    @classmethod
    def setUpTestData(self):
        Author.objects.create(name="Bob", age=1, alias="1")

    def test_cast_from_value(self):
        numbers = Author.objects.annotate(
            cast_integer=Cast(models.Value("0"), models.IntegerField())
        )
        self.assertEqual(numbers.get().cast_integer, 0)

    def test_cast_from_field(self):
        numbers = Author.objects.annotate(
            cast_string=Cast("age", models.CharField(max_length=255)),
        )
        self.assertEqual(numbers.get().cast_string, "1")

    def test_cast_to_char_field_without_max_length(self):
        numbers = Author.objects.annotate(cast_string=Cast("age", models.CharField()))
        self.assertEqual(numbers.get().cast_string, "1")

    # Silence "Truncated incorrect CHAR(1) value: 'Bob'".
    @ignore_warnings(module="django.db.backends.mysql.base")
    @skipUnlessDBFeature("supports_cast_with_precision")
    def test_cast_to_char_field_with_max_length(self):
        names = Author.objects.annotate(
            cast_string=Cast("name", models.CharField(max_length=1))
        )
        self.assertEqual(names.get().cast_string, "B")

    @skipUnlessDBFeature("supports_cast_with_precision")
    def test_cast_to_decimal_field(self):
        FloatModel.objects.create(f1=-1.934, f2=3.467)
        float_obj = FloatModel.objects.annotate(
            cast_f1_decimal=Cast(
                "f1", models.DecimalField(max_digits=8, decimal_places=2)
            ),
            cast_f2_decimal=Cast(
                "f2", models.DecimalField(max_digits=8, decimal_places=1)
            ),
        ).get()
        self.assertEqual(float_obj.cast_f1_decimal, decimal.Decimal("-1.93"))
        expected = "3.4" if connection.features.rounds_to_even else "3.5"
        self.assertEqual(float_obj.cast_f2_decimal, decimal.Decimal(expected))
        author_obj = Author.objects.annotate(
            cast_alias_decimal=Cast(
                "alias", models.DecimalField(max_digits=8, decimal_places=2)
            ),
        ).get()
        self.assertEqual(author_obj.cast_alias_decimal, decimal.Decimal("1"))

    def test_cast_to_integer(self):
        for field_class in (
            models.AutoField,
            models.BigAutoField,
            models.SmallAutoField,
            models.IntegerField,
            models.BigIntegerField,
            models.SmallIntegerField,
            models.PositiveBigIntegerField,
            models.PositiveIntegerField,
            models.PositiveSmallIntegerField,
        ):
            with self.subTest(field_class=field_class):
                numbers = Author.objects.annotate(cast_int=Cast("alias", field_class()))
                self.assertEqual(numbers.get().cast_int, 1)

    def test_cast_to_integer_foreign_key(self):
        numbers = Author.objects.annotate(
            cast_fk=Cast(
                models.Value("0"),
                models.ForeignKey(Author, on_delete=models.SET_NULL),
            )
        )
        self.assertEqual(numbers.get().cast_fk, 0)

    def test_cast_to_duration(self):
        duration = datetime.timedelta(days=1, seconds=2, microseconds=3)
        DTModel.objects.create(duration=duration)
        dtm = DTModel.objects.annotate(
            cast_duration=Cast("duration", models.DurationField()),
            cast_neg_duration=Cast(-duration, models.DurationField()),
        ).get()
        self.assertEqual(dtm.cast_duration, duration)
        self.assertEqual(dtm.cast_neg_duration, -duration)

    def test_cast_from_db_datetime_to_date(self):
        dt_value = datetime.datetime(2018, 9, 28, 12, 42, 10, 234567)
        DTModel.objects.create(start_datetime=dt_value)
        dtm = DTModel.objects.annotate(
            start_datetime_as_date=Cast("start_datetime", models.DateField())
        ).first()
        self.assertEqual(dtm.start_datetime_as_date, datetime.date(2018, 9, 28))

    def test_cast_from_db_datetime_to_time(self):
        dt_value = datetime.datetime(2018, 9, 28, 12, 42, 10, 234567)
        DTModel.objects.create(start_datetime=dt_value)
        dtm = DTModel.objects.annotate(
            start_datetime_as_time=Cast("start_datetime", models.TimeField())
        ).first()
        rounded_ms = int(
            round(0.234567, connection.features.time_cast_precision) * 10**6
        )
        self.assertEqual(
            dtm.start_datetime_as_time, datetime.time(12, 42, 10, rounded_ms)
        )

    def test_cast_from_db_date_to_datetime(self):
        dt_value = datetime.date(2018, 9, 28)
        DTModel.objects.create(start_date=dt_value)
        dtm = DTModel.objects.annotate(
            start_as_datetime=Cast("start_date", models.DateTimeField())
        ).first()
        self.assertEqual(
            dtm.start_as_datetime, datetime.datetime(2018, 9, 28, 0, 0, 0, 0)
        )

    def test_cast_from_db_datetime_to_date_group_by(self):
        author = Author.objects.create(name="John Smith", age=45)
        dt_value = datetime.datetime(2018, 9, 28, 12, 42, 10, 234567)
        Fan.objects.create(name="Margaret", age=50, author=author, fan_since=dt_value)
        fans = (
            Fan.objects.values("author")
            .annotate(
                fan_for_day=Cast("fan_since", models.DateField()),
                fans=models.Count("*"),
            )
            .values()
        )
        self.assertEqual(fans[0]["fan_for_day"], datetime.date(2018, 9, 28))
        self.assertEqual(fans[0]["fans"], 1)

    def test_cast_from_python_to_date(self):
        today = datetime.date.today()
        dates = Author.objects.annotate(cast_date=Cast(today, models.DateField()))
        self.assertEqual(dates.get().cast_date, today)

    def test_cast_from_python_to_datetime(self):
        now = datetime.datetime.now()
        dates = Author.objects.annotate(cast_datetime=Cast(now, models.DateTimeField()))
        time_precision = datetime.timedelta(
            microseconds=10 ** (6 - connection.features.time_cast_precision)
        )
        self.assertAlmostEqual(dates.get().cast_datetime, now, delta=time_precision)

    def test_cast_from_python(self):
        numbers = Author.objects.annotate(
            cast_float=Cast(decimal.Decimal(0.125), models.FloatField())
        )
        cast_float = numbers.get().cast_float
        self.assertIsInstance(cast_float, float)
        self.assertEqual(cast_float, 0.125)

    @unittest.skipUnless(connection.vendor == "postgresql", "PostgreSQL test")
    def test_expression_wrapped_with_parentheses_on_postgresql(self):
        """
        The SQL for the Cast expression is wrapped with parentheses in case
        it's a complex expression.
        """
        with CaptureQueriesContext(connection) as captured_queries:
            list(
                Author.objects.annotate(
                    cast_float=Cast(models.Avg("age"), models.FloatField()),
                )
            )
        self.assertIn(
            '(AVG("db_functions_author"."age"))::double precision',
            captured_queries[0]["sql"],
        )

    def test_cast_to_text_field(self):
        self.assertEqual(
            Author.objects.values_list(
                Cast("age", models.TextField()), flat=True
            ).get(),
            "1",
        )