[1.7.x] Fixed #22489 -- missing implemenation for search lookup

When custom lookups were added, converting the search lookup to use
the new Lookup infrastructure wasn't done.

Some changes were needed to the added test, main change done by
committer was ensuring the test works on MySQL versions prior to 5.6.

Backport of 7131e14d00 from master

django/db/models/lookups.py

@@ -358,6 +358,13 @@ default_lookups['isnull'] = IsNull
 
 class Search(BuiltinLookup):
     lookup_name = 'search'
+
+    def as_sql(self, qn, connection):
+        lhs, lhs_params = self.process_lhs(qn, connection)
+        rhs, rhs_params = self.process_rhs(qn, connection)
+        sql_template = connection.ops.fulltext_search_sql(field_name=lhs)
+        return sql_template, lhs_params + rhs_params
+
 default_lookups['search'] = Search
 
 

tests/lookup/models.py

@@ -65,3 +65,15 @@ class Player(models.Model):
 
     def __str__(self):
         return self.name
+
+
+# To test __search lookup a fulltext index is needed. This
+# is only available when using MySQL 5.6, or when using MyISAM
+# tables. As 5.6 isn't common yet, lets use MyISAM table for
+# testing. The table is manually created by the test method.
+class MyISAMArticle(models.Model):
+    headline = models.CharField(max_length=100)
+
+    class Meta:
+        db_table = 'myisam_article'
+        managed = False

tests/lookup/tests.py

@@ -2,11 +2,13 @@ from __future__ import unicode_literals
 
 from datetime import datetime
 from operator import attrgetter
+from unittest import skipUnless
 
 from django.core.exceptions import FieldError
-from django.test import TestCase, skipUnlessDBFeature
+from django.db import connection
+from django.test import TestCase, TransactionTestCase, skipUnlessDBFeature
 
-from .models import Author, Article, Tag, Game, Season, Player
+from .models import Author, Article, Tag, Game, Season, Player, MyISAMArticle
 
 
 class LookupTests(TestCase):
@@ -710,3 +712,27 @@ class LookupTests(TestCase):
         self.assertEqual(Player.objects.filter(games__season__gt=333).distinct().count(), 2)
         self.assertEqual(Player.objects.filter(games__season__year__gt=2010).distinct().count(), 2)
         self.assertEqual(Player.objects.filter(games__season__gt__gt=222).distinct().count(), 2)
+
+
+class LookupTransactionTests(TransactionTestCase):
+    available_apps = ['lookup']
+
+    @skipUnless(connection.vendor == 'mysql', 'requires MySQL')
+    def test_mysql_lookup_search(self):
+        # To use fulltext indexes on MySQL either version 5.6 is needed, or one must use
+        # MyISAM tables. Neither of these combinations is currently available on CI, so
+        # lets manually create a MyISAM table for Article model.
+        with connection.cursor() as cursor:
+            cursor.execute(
+                "CREATE TEMPORARY TABLE myisam_article ("
+                "    id INTEGER PRIMARY KEY AUTO_INCREMENT, "
+                "    headline VARCHAR(100) NOT NULL "
+                ") ENGINE MYISAM")
+            dr = MyISAMArticle.objects.create(headline='Django Reinhardt')
+            MyISAMArticle.objects.create(headline='Ringo Star')
+            # NOTE: Needs to be created after the article has been saved.
+            cursor.execute(
+                'CREATE FULLTEXT INDEX myisam_article_ft ON myisam_article (headline)')
+            self.assertQuerysetEqual(
+                MyISAMArticle.objects.filter(headline__search='Reinhardt'),
+                [dr], lambda x: x)