From 5ca67eca21d2adfb418f96b63e7d3de237737a1e Mon Sep 17 00:00:00 2001
From: Prem Sichanugrist <s@sikachu.com>
Date: Sun, 15 May 2011 14:19:09 -0400
Subject: [PATCH] Add ActiveRecord::attribute_names to retrieve a list of
 attribute names. This method will also return an empty array on an abstract
 class or a model that the table doesn't exists.

---
 activerecord/CHANGELOG                 |  2 ++
 activerecord/lib/active_record/base.rb |  8 ++++++++
 activerecord/test/cases/base_test.rb   | 13 +++++++++++++
 3 files changed, 23 insertions(+)

diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG
index 32bcf02139..2e144745cd 100644
--- a/activerecord/CHANGELOG
+++ b/activerecord/CHANGELOG
@@ -1,5 +1,7 @@
 *Rails 3.1.0 (unreleased)*
 
+* Add ActiveRecord::Base.attribute_names to return a list of attribute names. This will return an empty array if the model is abstract or table does not exists. [Prem Sichanugrist]
+
 * CSV Fixtures are deprecated and support will be removed in Rails 3.2.0
 
 * AR#new, AR#create, AR#create!, AR#update_attributes and AR#update_attributes! all accept a second hash as option that allows you
diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index e1bf2ccc8a..cfe6d8d2de 100644
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -767,6 +767,14 @@ def attribute_method?(attribute)
         super || (table_exists? && column_names.include?(attribute.to_s.sub(/=$/, '')))
       end
 
+      def attribute_names
+        @attribute_names ||= if !abstract_class? && table_exists?
+            column_names
+          else
+            []
+          end
+      end
+
       # Set the lookup ancestors for ActiveModel.
       def lookup_ancestors #:nodoc:
         klass = self
diff --git a/activerecord/test/cases/base_test.rb b/activerecord/test/cases/base_test.rb
index 9bc04ed29c..bfb66f07da 100644
--- a/activerecord/test/cases/base_test.rb
+++ b/activerecord/test/cases/base_test.rb
@@ -1790,4 +1790,17 @@ def test_marshal_round_trip
 
     assert_equal expected.attributes, actual.attributes
   end
+
+  def test_attribute_names
+    assert_equal ["id", "type", "ruby_type", "firm_id", "firm_name", "name", "client_of", "rating", "account_id"],
+                 Company.attribute_names
+  end
+
+  def test_attribute_names_on_table_not_exists
+    assert_equal [], NonExistentTable.attribute_names
+  end
+
+  def test_attribtue_names_on_abstract_class
+    assert_equal [], AbstractCompany.attribute_names
+  end
 end
-- 
GitLab