django/tests/db_functions/test_right.py

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from django.db.models import CharField, Value
from django.db.models.functions import 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_expressions(self):
authors = Author.objects.annotate(name_part=Right('name', Value(3), output_field=CharField()))
self.assertQuerysetEqual(authors.order_by('name'), ['ith', 'nda'], lambda a: a.name_part)