1. from django.db.models import F, Value

  2. from django.db.models.functions import Concat, Replace

  3. from django.test import TestCase

  4. 

  5. from ..models import Author

  6. 

  7. 

  8. class ReplaceTests(TestCase):

  9.     @classmethod

  10.     def setUpTestData(cls):

  11.         Author.objects.create(name="George R. R. Martin")

  12.         Author.objects.create(name="J. R. R. Tolkien")

  13. 

  14.     def test_replace_with_empty_string(self):

  15.         qs = Author.objects.annotate(

  16.             without_middlename=Replace(F("name"), Value("R. R. "), Value("")),

  17.         )

  18.         self.assertQuerysetEqual(

  19.             qs,

  20.             [

  21.                 ("George R. R. Martin", "George Martin"),

  22.                 ("J. R. R. Tolkien", "J. Tolkien"),

  23.             ],

  24.             transform=lambda x: (x.name, x.without_middlename),

  25.             ordered=False,

  26.         )

  27. 

  28.     def test_case_sensitive(self):

  29.         qs = Author.objects.annotate(

  30.             same_name=Replace(F("name"), Value("r. r."), Value(""))

  31.         )

  32.         self.assertQuerysetEqual(

  33.             qs,

  34.             [

  35.                 ("George R. R. Martin", "George R. R. Martin"),

  36.                 ("J. R. R. Tolkien", "J. R. R. Tolkien"),

  37.             ],

  38.             transform=lambda x: (x.name, x.same_name),

  39.             ordered=False,

  40.         )

  41. 

  42.     def test_replace_expression(self):

  43.         qs = Author.objects.annotate(

  44.             same_name=Replace(

  45.                 Concat(Value("Author: "), F("name")), Value("Author: "), Value("")

  46.             ),

  47.         )

  48.         self.assertQuerysetEqual(

  49.             qs,

  50.             [

  51.                 ("George R. R. Martin", "George R. R. Martin"),

  52.                 ("J. R. R. Tolkien", "J. R. R. Tolkien"),

  53.             ],

  54.             transform=lambda x: (x.name, x.same_name),

  55.             ordered=False,

  56.         )

  57. 

  58.     def test_update(self):

  59.         Author.objects.update(

  60.             name=Replace(F("name"), Value("R. R. "), Value("")),

  61.         )

  62.         self.assertQuerysetEqual(

  63.             Author.objects.all(),

  64.             [

  65.                 ("George Martin"),

  66.                 ("J. Tolkien"),

  67.             ],

  68.             transform=lambda x: x.name,

  69.             ordered=False,

  70.         )

  71. 

  72.     def test_replace_with_default_arg(self):

  73.         # The default replacement is an empty string.

  74.         qs = Author.objects.annotate(same_name=Replace(F("name"), Value("R. R. ")))

  75.         self.assertQuerysetEqual(

  76.             qs,

  77.             [

  78.                 ("George R. R. Martin", "George Martin"),

  79.                 ("J. R. R. Tolkien", "J. Tolkien"),

  80.             ],

  81.             transform=lambda x: (x.name, x.same_name),

  82.             ordered=False,

  83.         )
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