django/tests/db_functions/test_cast.py

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from django.db import models
from django.db.models.expressions import Value
from django.db.models.functions import Cast
from django.test import TestCase, ignore_warnings, skipUnlessDBFeature
from .models import Author
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(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')
# 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')
def test_cast_to_integer(self):
for field_class in (
models.IntegerField,
models.BigIntegerField,
models.SmallIntegerField,
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_from_python(self):
numbers = Author.objects.annotate(cast_float=Cast(0, models.FloatField()))
self.assertEqual(numbers.get().cast_float, 0.0)