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28 lines
1.2 KiB
Python
28 lines
1.2 KiB
Python
from django.db.models import CharField, 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(authors.order_by('name'), ['John ', 'Rhond'], lambda a: a.name_part)
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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(authors.order_by('name'), ['smithj', 'rh'], lambda a: a.alias)
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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(name_part=Left('name', Value(3), output_field=CharField()))
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self.assertQuerysetEqual(authors.order_by('name'), ['Joh', 'Rho'], lambda a: a.name_part)
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