[1.11.x] Fixed #28702 -- Made query lookups for CIText fields use citext.

Backport of f0a68c25118786d47041d0a435b2afa953be3c86 from master

5 files changed, 34 insertions, 3 deletions

diff --git a/django/contrib/postgres/fields/citext.py b/django/contrib/postgres/fields/citext.py
index 42660001ae..f5ef86c586 100644
--- a/django/contrib/postgres/fields/citext.py
+++ b/django/contrib/postgres/fields/citext.py
@@ -3,7 +3,11 @@ from django.db.models import CharField, EmailField, TextField
 __all__ = ['CICharField', 'CIEmailField', 'CIText', 'CITextField']
 
 
-class CIText:
+class CIText(object):
+
+    def get_internal_type(self):
+        return 'CI' + super(CIText, self).get_internal_type()
+
     def db_type(self, connection):
         return 'citext'
 
diff --git a/django/db/backends/postgresql/operations.py b/django/db/backends/postgresql/operations.py
index a66cb0c563..f220639725 100644
--- a/django/db/backends/postgresql/operations.py
+++ b/django/db/backends/postgresql/operations.py
@@ -83,6 +83,8 @@ class DatabaseOperations(BaseDatabaseOperations):
                            'istartswith', 'endswith', 'iendswith', 'regex', 'iregex'):
             if internal_type in ('IPAddressField', 'GenericIPAddressField'):
                 lookup = "HOST(%s)"
+            elif internal_type in ('CICharField', 'CIEmailField', 'CITextField'):
+                lookup = '%s::citext'
             else:
                 lookup = "%s::text"
 
diff --git a/docs/releases/1.11.8.txt b/docs/releases/1.11.8.txt
index 6f744a6886..959731bbd5 100644
--- a/docs/releases/1.11.8.txt
+++ b/docs/releases/1.11.8.txt
@@ -24,3 +24,6 @@ Bugfixes
 
 * Fixed crash on SQLite and MySQL when ordering by a filtered subquery that
   uses ``nulls_first`` or ``nulls_last`` (:ticket:`28848`).
+
+* Made query lookups for ``CICharField``, ``CIEmailField``, and ``CITextField``
+  use a ``citext`` cast (:ticket:`28702`).
diff --git a/tests/backends/tests.py b/tests/backends/tests.py
index 16a20de40d..2217669354 100644
--- a/tests/backends/tests.py
+++ b/tests/backends/tests.py
@@ -377,9 +377,15 @@ class PostgreSQLTests(TestCase):
         from django.db.backends.postgresql.operations import DatabaseOperations
 
         do = DatabaseOperations(connection=None)
-        for lookup in ('iexact', 'contains', 'icontains', 'startswith',
-                       'istartswith', 'endswith', 'iendswith', 'regex', 'iregex'):
+        lookups = (
+            'iexact', 'contains', 'icontains', 'startswith', 'istartswith',
+            'endswith', 'iendswith', 'regex', 'iregex',
+        )
+        for lookup in lookups:
             self.assertIn('::text', do.lookup_cast(lookup))
+        for lookup in lookups:
+            for field_type in ('CICharField', 'CIEmailField', 'CITextField'):
+                self.assertIn('::citext', do.lookup_cast(lookup, internal_type=field_type))
 
     def test_correct_extraction_psycopg2_version(self):
         from django.db.backends.postgresql.base import psycopg2_version
diff --git a/tests/postgres_tests/test_citext.py b/tests/postgres_tests/test_citext.py
index 0a7012b072..22dc9e7431 100644
--- a/tests/postgres_tests/test_citext.py
+++ b/tests/postgres_tests/test_citext.py
@@ -12,6 +12,7 @@ from .models import CITestModel
 
 @modify_settings(INSTALLED_APPS={'append': 'django.contrib.postgres'})
 class CITextTestCase(PostgreSQLTestCase):
+    case_sensitive_lookups = ('contains', 'startswith', 'endswith', 'regex')
 
     @classmethod
     def setUpTestData(cls):
@@ -42,3 +43,18 @@ class CITextTestCase(PostgreSQLTestCase):
         instance = CITestModel.objects.get()
         self.assertEqual(instance.array_field, self.john.array_field)
         self.assertTrue(CITestModel.objects.filter(array_field__contains=['joe']).exists())
+
+    def test_lookups_name_char(self):
+        for lookup in self.case_sensitive_lookups:
+            query = {'name__{}'.format(lookup): 'john'}
+            self.assertSequenceEqual(CITestModel.objects.filter(**query), [self.john])
+
+    def test_lookups_description_text(self):
+        for lookup, string in zip(self.case_sensitive_lookups, ('average', 'average joe', 'john', 'Joe.named')):
+            query = {'description__{}'.format(lookup): string}
+            self.assertSequenceEqual(CITestModel.objects.filter(**query), [self.john])
+
+    def test_lookups_email(self):
+        for lookup, string in zip(self.case_sensitive_lookups, ('john', 'john', 'john.com', 'john.com')):
+            query = {'email__{}'.format(lookup): string}
+            self.assertSequenceEqual(CITestModel.objects.filter(**query), [self.john])