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from django.db import connection
from django.db.models import IntegerField, Value
from django.db.models.functions import Length, Lower, Right
from django.test import TestCase
from ..models import Author
class RightTests(TestCase):
@classmethod
def setUpTestData(cls):
Author.objects.create(name="John Smith", alias="smithj")
Author.objects.create(name="Rhonda")
def test_basic(self):
authors = Author.objects.annotate(name_part=Right("name", 5))
self.assertQuerySetEqual(
authors.order_by("name"), ["Smith", "honda"], lambda a: a.name_part
)
# If alias is null, set it to the first 2 lower characters of the name.
Author.objects.filter(alias__isnull=True).update(alias=Lower(Right("name", 2)))
self.assertQuerySetEqual(
authors.order_by("name"), ["smithj", "da"], lambda a: a.alias
)
def test_invalid_length(self):
with self.assertRaisesMessage(ValueError, "'length' must be greater than 0"):
Author.objects.annotate(raises=Right("name", 0))
def test_zero_length(self):
Author.objects.create(name="Tom", alias="tom")
authors = Author.objects.annotate(
name_part=Right("name", Length("name") - Length("alias"))
)
self.assertQuerySetEqual(
authors.order_by("name"),
[
"mith",
"" if connection.features.interprets_empty_strings_as_nulls else None,
"",
],
lambda a: a.name_part,
)
def test_expressions(self):
authors = Author.objects.annotate(
name_part=Right("name", Value(3, output_field=IntegerField()))
)
self.assertQuerySetEqual(
authors.order_by("name"), ["ith", "nda"], lambda a: a.name_part
)
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