Fixed #27834 -- Added StrIndex database function.

tests/db_functions/test_strindex.py

@@ -0,0 +1,65 @@
+from django.db.models.functions import StrIndex
+from django.test import TestCase
+from django.utils import timezone
+
+from .models import Article, Author
+
+
+class StrIndexTests(TestCase):
+    def test_annotate_charfield(self):
+        Author.objects.create(name='George. R. R. Martin')
+        Author.objects.create(name='J. R. R. Tolkien')
+        Author.objects.create(name='Terry Pratchett')
+        authors = Author.objects.annotate(fullstop=StrIndex('name', 'R.'))
+        self.assertQuerysetEqual(authors.order_by('name'), [9, 4, 0], lambda a: a.fullstop)
+
+    def test_annotate_textfield(self):
+        Article.objects.create(
+            title='How to Django',
+            text='Lorem ipsum dolor sit amet.',
+            written=timezone.now(),
+        )
+        Article.objects.create(
+            title='How to Tango',
+            text="Won't find anything here.",
+            written=timezone.now(),
+        )
+        articles = Article.objects.annotate(ipsum_index=StrIndex('text', 'ipsum'))
+        self.assertQuerysetEqual(articles.order_by('title'), [7, 0], lambda a: a.ipsum_index)
+
+    def test_order_by(self):
+        Author.objects.create(name='Terry Pratchett')
+        Author.objects.create(name='J. R. R. Tolkien')
+        Author.objects.create(name='George. R. R. Martin')
+        self.assertQuerysetEqual(
+            Author.objects.order_by(StrIndex('name', 'R.').asc()), [
+                'Terry Pratchett',
+                'J. R. R. Tolkien',
+                'George. R. R. Martin',
+            ],
+            lambda a: a.name
+        )
+        self.assertQuerysetEqual(
+            Author.objects.order_by(StrIndex('name', 'R.').desc()), [
+                'George. R. R. Martin',
+                'J. R. R. Tolkien',
+                'Terry Pratchett',
+            ],
+            lambda a: a.name
+        )
+
+    def test_unicode_values(self):
+        Author.objects.create(name='ツリー')
+        Author.objects.create(name='皇帝')
+        Author.objects.create(name='皇帝 ツリー')
+        authors = Author.objects.annotate(sb=StrIndex('name', 'リ'))
+        self.assertQuerysetEqual(authors.order_by('name'), [2, 0, 5], lambda a: a.sb)
+
+    def test_filtering(self):
+        Author.objects.create(name='George. R. R. Martin')
+        Author.objects.create(name='Terry Pratchett')
+        self.assertQuerysetEqual(
+            Author.objects.annotate(middle_name=StrIndex('name', 'R.')).filter(middle_name__gt=0),
+            ['George. R. R. Martin'],
+            lambda a: a.name
+        )