From 9cc324a3f1348430e5b6db58bbddab5090c708c8 Mon Sep 17 00:00:00 2001
From: Sean Griffin <sean@seantheprogrammer.com>
Date: Mon, 21 Sep 2015 11:14:32 -0600
Subject: [PATCH] Ensure aliased attributes passed to `select` are quoted if
 using `from`

Fixes #21488

[Sean Griffin & johanlunds]
---
 activerecord/CHANGELOG.md                              |  6 ++++++
 .../lib/active_record/relation/query_methods.rb        |  2 +-
 activerecord/test/cases/relations_test.rb              | 10 ++++++++++
 activerecord/test/schema/schema.rb                     |  4 ++++
 4 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 1b016b6e8b..8befdfcdba 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,9 @@
+*   Ensure `select` quotes aliased attributes, even when using `from`.
+
+    Fixes #21488
+
+    *Sean Griffin & @johanlunds*
+
 *   MySQL: support `unsigned` numeric data types.
 
     Example:
diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index e25b889851..038280509d 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -250,7 +250,7 @@ def select(*fields)
     def _select!(*fields) # :nodoc:
       fields.flatten!
       fields.map! do |field|
-        klass.attribute_alias?(field) ? klass.attribute_alias(field) : field
+        klass.attribute_alias?(field) ? klass.attribute_alias(field).to_sym : field
       end
       self.select_values += fields
       self
diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index 8256762f96..5aa0ea85a5 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -1897,4 +1897,14 @@ def test_merging_reorders_bind_params
   def test_relation_join_method
     assert_equal 'Thank you for the welcome,Thank you again for the welcome', Post.first.comments.join(",")
   end
+
+  def test_selecting_aliased_attribute_quotes_column_name_when_from_is_used
+    klass = Class.new(ActiveRecord::Base) do
+      self.table_name = :test_with_keyword_column_name
+      alias_attribute :description, :desc
+    end
+    klass.create!(description: "foo")
+
+    assert_equal ["foo"], klass.select(:description).from(klass.all).map(&:desc)
+  end
 end
diff --git a/activerecord/test/schema/schema.rb b/activerecord/test/schema/schema.rb
index df1834d381..d318f3a968 100644
--- a/activerecord/test/schema/schema.rb
+++ b/activerecord/test/schema/schema.rb
@@ -943,6 +943,10 @@ def except(adapter_names_to_exclude)
     t.string :token
     t.string :auth_token
   end
+
+  create_table :test_with_keyword_column_name, force: true do |t|
+    t.string :desc
+  end
 end
 
 Course.connection.create_table :courses, force: true do |t|