From f6ff024b80863031bf67477b62c14390a19d8110 Mon Sep 17 00:00:00 2001
From: Konsta Vesterinen <konsta.vesterinen@gmail.com>
Date: Fri, 24 Oct 2014 14:19:21 +0300
Subject: [PATCH] Fix alias handling in has_index

---
 CHANGES.rst                            |  1 +
 sqlalchemy_utils/functions/database.py | 10 ++++++++--
 tests/functions/test_has_index.py      |  6 ++++++
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/CHANGES.rst b/CHANGES.rst
index e9aaf2e..8b5eebb 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -9,6 +9,7 @@ Here you can see the full list of changes between each SQLAlchemy-Utils release.
 
 - Made assert_* functions automatically rollback session
 - Fix alias handling in has_unique_index
+- Fix alias handling in has_index
 
 
 0.27.4 (2014-10-23)
diff --git a/sqlalchemy_utils/functions/database.py b/sqlalchemy_utils/functions/database.py
index aa4003e..6748f27 100644
--- a/sqlalchemy_utils/functions/database.py
+++ b/sqlalchemy_utils/functions/database.py
@@ -159,12 +159,18 @@ def has_index(column):
         has_index(table.c.locale)   # False
         has_index(table.c.id)       # True
     """
+    table = column.table
+    if not isinstance(table, sa.Table):
+        raise TypeError(
+            'Only columns belonging to Table objects are supported. Given '
+            'column belongs to %r.' % table
+        )
     return (
-        column is column.table.primary_key.columns.values()[0]
+        column is table.primary_key.columns.values()[0]
         or
         any(
             index.columns.values()[0] is column
-            for index in column.table.indexes
+            for index in table.indexes
         )
     )
 
diff --git a/tests/functions/test_has_index.py b/tests/functions/test_has_index.py
index 43f0474..3dfabf1 100644
--- a/tests/functions/test_has_index.py
+++ b/tests/functions/test_has_index.py
@@ -1,4 +1,5 @@
 import sqlalchemy as sa
+from pytest import raises
 from sqlalchemy.ext.declarative import declarative_base
 
 from sqlalchemy_utils import has_index
@@ -23,6 +24,11 @@ class TestHasIndex(object):
 
         self.table = ArticleTranslation.__table__
 
+    def test_column_that_belongs_to_an_alias(self):
+        alias = sa.orm.aliased(self.table)
+        with raises(TypeError):
+            assert has_index(alias.c.id)
+
     def test_compound_primary_key(self):
         assert has_index(self.table.c.id)
         assert not has_index(self.table.c.locale)