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36 lines
1.3 KiB
Python
36 lines
1.3 KiB
Python
from django.db.models import IntegerField, Value
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from django.db.models.functions import Left, Lower
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from django.test import TestCase
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from ..models import Author
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class LeftTests(TestCase):
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@classmethod
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def setUpTestData(cls):
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Author.objects.create(name="John Smith", alias="smithj")
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Author.objects.create(name="Rhonda")
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def test_basic(self):
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authors = Author.objects.annotate(name_part=Left("name", 5))
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self.assertQuerySetEqual(
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authors.order_by("name"), ["John ", "Rhond"], lambda a: a.name_part
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)
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# If alias is null, set it to the first 2 lower characters of the name.
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Author.objects.filter(alias__isnull=True).update(alias=Lower(Left("name", 2)))
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self.assertQuerySetEqual(
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authors.order_by("name"), ["smithj", "rh"], lambda a: a.alias
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)
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def test_invalid_length(self):
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with self.assertRaisesMessage(ValueError, "'length' must be greater than 0"):
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Author.objects.annotate(raises=Left("name", 0))
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def test_expressions(self):
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authors = Author.objects.annotate(
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name_part=Left("name", Value(3, output_field=IntegerField()))
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)
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self.assertQuerySetEqual(
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authors.order_by("name"), ["Joh", "Rho"], lambda a: a.name_part
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)
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