Refs #26709 -- Added type check for models.Index fields argument.

2 files changed, 6 insertions, 0 deletions

diff --git a/django/db/models/indexes.py b/django/db/models/indexes.py
index f70c2e5625..2396ba2819 100644
--- a/django/db/models/indexes.py
+++ b/django/db/models/indexes.py
@@ -14,6 +14,8 @@ class Index(object):
     suffix = 'idx'
 
     def __init__(self, fields=[], name=None):
+        if not isinstance(fields, list):
+            raise ValueError('Index.fields must be a list.')
         if not fields:
             raise ValueError('At least one field is required to define an index.')
         self.fields = fields
diff --git a/tests/model_indexes/tests.py b/tests/model_indexes/tests.py
index 52db494905..0e276dbd15 100644
--- a/tests/model_indexes/tests.py
+++ b/tests/model_indexes/tests.py
@@ -22,6 +22,10 @@ class IndexesTests(TestCase):
         self.assertEqual(index, same_index)
         self.assertNotEqual(index, another_index)
 
+    def test_index_fields_type(self):
+        with self.assertRaisesMessage(ValueError, 'Index.fields must be a list.'):
+            models.Index(fields='title')
+
     def test_raises_error_without_field(self):
         msg = 'At least one field is required to define an index.'
         with self.assertRaisesMessage(ValueError, msg):