[1.11.x] Fixed #27135 -- Made index introspection return Index.suffix.

Backport of b008f7cc56 from master

django/db/backends/mysql/introspection.py

@@ -6,6 +6,7 @@ from MySQLdb.constants import FIELD_TYPE
 from django.db.backends.base.introspection import (
     BaseDatabaseIntrospection, FieldInfo, TableInfo,
 )
+from django.db.models.indexes import Index
 from django.utils.datastructures import OrderedSet
 from django.utils.deprecation import RemovedInDjango21Warning
 from django.utils.encoding import force_text
@@ -217,7 +218,7 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
                     'foreign_key': None,
                 }
             constraints[index]['index'] = True
-            constraints[index]['type'] = type_.lower()
+            constraints[index]['type'] = Index.suffix if type_ == 'BTREE' else type_.lower()
             constraints[index]['columns'].add(column)
         # Convert the sorted sets to lists
         for constraint in constraints.values():

django/db/backends/oracle/introspection.py

@@ -281,7 +281,7 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
                     "foreign_key": None,
                     "check": False,
                     "index": True,
-                    "type": 'btree' if type_ == 'normal' else type_,
+                    "type": 'idx' if type_ == 'normal' else type_,
                 }
             # Record the details
             constraints[constraint]['columns'].append(column)

django/db/backends/postgresql/introspection.py

@@ -5,6 +5,7 @@ import warnings
 from django.db.backends.base.introspection import (
     BaseDatabaseIntrospection, FieldInfo, TableInfo,
 )
+from django.db.models.indexes import Index
 from django.utils.deprecation import RemovedInDjango21Warning
 from django.utils.encoding import force_text
 
@@ -236,7 +237,7 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
                     "foreign_key": None,
                     "check": False,
                     "index": True,
-                    "type": type_,
+                    "type": Index.suffix if type_ == 'btree' else type_,
                     "definition": definition,
                     "options": options,
                 }

django/db/backends/sqlite3/introspection.py

@@ -4,6 +4,7 @@ import warnings
 from django.db.backends.base.introspection import (
     BaseDatabaseIntrospection, FieldInfo, TableInfo,
 )
+from django.db.models.indexes import Index
 from django.utils.deprecation import RemovedInDjango21Warning
 
 field_size_re = re.compile(r'^\s*(?:var)?char\s*\(\s*(\d+)\s*\)\s*$')
@@ -262,7 +263,7 @@ class DatabaseIntrospection(BaseDatabaseIntrospection):
             # Add type and column orders for indexes
             if constraints[index]['index'] and not constraints[index]['unique']:
                 # SQLite doesn't support any index type other than b-tree
-                constraints[index]['type'] = 'btree'
+                constraints[index]['type'] = Index.suffix
                 cursor.execute(
                     "SELECT sql FROM sqlite_master "
                     "WHERE type='index' AND name=%s" % self.connection.ops.quote_name(index)

tests/introspection/tests.py

@@ -3,6 +3,7 @@ from __future__ import unicode_literals
 from unittest import skipUnless
 
 from django.db import connection
+from django.db.models import Index
 from django.db.utils import DatabaseError
 from django.test import TransactionTestCase, mock, skipUnlessDBFeature
 from django.test.utils import ignore_warnings
@@ -193,7 +194,7 @@ class IntrospectionTests(TransactionTestCase):
         for key, val in constraints.items():
             if val['columns'] == ['headline', 'pub_date']:
                 index = val
-        self.assertEqual(index['type'], 'btree')
+        self.assertEqual(index['type'], Index.suffix)
 
     @skipUnlessDBFeature('supports_index_column_ordering')
     def test_get_constraints_indexes_orders(self):

tests/model_indexes/tests.py

@@ -1,10 +1,13 @@
 from django.db import models
-from django.test import TestCase
+from django.test import SimpleTestCase
 
 from .models import Book
 
 
-class IndexesTests(TestCase):
+class IndexesTests(SimpleTestCase):
+
+    def test_suffix(self):
+        self.assertEqual(models.Index.suffix, 'idx')
 
     def test_repr(self):
         index = models.Index(fields=['title'])

tests/postgres_tests/test_indexes.py

@@ -9,6 +9,9 @@ from .models import CharFieldModel, IntegerArrayModel
 @skipUnlessDBFeature('has_brin_index_support')
 class BrinIndexTests(PostgreSQLTestCase):
 
+    def test_suffix(self):
+        self.assertEqual(BrinIndex.suffix, 'brin')
+
     def test_repr(self):
         index = BrinIndex(fields=['title'], pages_per_range=4)
         another_index = BrinIndex(fields=['title'])
@@ -41,6 +44,9 @@ class BrinIndexTests(PostgreSQLTestCase):
 
 class GinIndexTests(PostgreSQLTestCase):
 
+    def test_suffix(self):
+        self.assertEqual(GinIndex.suffix, 'gin')
+
     def test_repr(self):
         index = GinIndex(fields=['title'])
         self.assertEqual(repr(index), "<GinIndex: fields='title'>")
@@ -84,7 +90,7 @@ class SchemaTests(PostgreSQLTestCase):
             editor.add_index(IntegerArrayModel, index)
         constraints = self.get_constraints(IntegerArrayModel._meta.db_table)
         # Check gin index was added
-        self.assertEqual(constraints[index_name]['type'], 'gin')
+        self.assertEqual(constraints[index_name]['type'], GinIndex.suffix)
         # Drop the index
         with connection.schema_editor() as editor:
             editor.remove_index(IntegerArrayModel, index)
@@ -97,7 +103,7 @@ class SchemaTests(PostgreSQLTestCase):
         with connection.schema_editor() as editor:
             editor.add_index(CharFieldModel, index)
         constraints = self.get_constraints(CharFieldModel._meta.db_table)
-        self.assertEqual(constraints[index_name]['type'], 'brin')
+        self.assertEqual(constraints[index_name]['type'], BrinIndex.suffix)
         self.assertEqual(constraints[index_name]['options'], ['pages_per_range=4'])
         with connection.schema_editor() as editor:
             editor.remove_index(CharFieldModel, index)