From 6de710d6648e451ef47e9215172901e8d736ba0c Mon Sep 17 00:00:00 2001
From: Jessica Yao <jyao@college.harvard.edu>
Date: Mon, 21 Apr 2014 18:08:54 -0400
Subject: Fix inheritance of stored_attributes (fixes #14672)

[Brad Bennett, Jessica Yao, & Lakshmi Parthasarathy]
---
 activerecord/CHANGELOG.md               |  7 +++++++
 activerecord/lib/active_record/store.rb | 19 ++++++++++++++-----
 activerecord/test/cases/store_test.rb   | 16 ++++++++++++++++
 3 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index f6cd5efb45..6d4ea2b682 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,10 @@
+*   Fix `stored_attributes` to correctly merge the details of stored
+    attributes defined in parent classes.
+
+    Fixes #14672.
+
+    *Brad Bennett*, *Jessica Yao*, *Lakshmi Parthasarathy*
+
 *   `change_column_default` allows `[]` as argument to `change_column_default`.
 
     Fixes #11586.
diff --git a/activerecord/lib/active_record/store.rb b/activerecord/lib/active_record/store.rb
index 79a6ccbda0..7014bc6d45 100644
--- a/activerecord/lib/active_record/store.rb
+++ b/activerecord/lib/active_record/store.rb
@@ -66,8 +66,9 @@ module ActiveRecord
     extend ActiveSupport::Concern
 
     included do
-      class_attribute :stored_attributes, instance_accessor: false
-      self.stored_attributes = {}
+      class << self
+        attr_accessor :local_stored_attributes
+      end
     end
 
     module ClassMethods
@@ -93,9 +94,9 @@ module ActiveRecord
 
         # assign new store attribute and create new hash to ensure that each class in the hierarchy
         # has its own hash of stored attributes.
-        self.stored_attributes = {} if self.stored_attributes.blank?
-        self.stored_attributes[store_attribute] ||= []
-        self.stored_attributes[store_attribute] |= keys
+        self.local_stored_attributes ||= {}
+        self.local_stored_attributes[store_attribute] ||= []
+        self.local_stored_attributes[store_attribute] |= keys
       end
 
       def _store_accessors_module
@@ -105,6 +106,14 @@ module ActiveRecord
           mod
         end
       end
+
+      def stored_attributes
+        parent = superclass.respond_to?(:stored_attributes) ? superclass.stored_attributes : {}
+        if self.local_stored_attributes
+          parent.merge!(self.local_stored_attributes) { |k, a, b| a | b }
+        end
+        parent
+      end
     end
 
     protected
diff --git a/activerecord/test/cases/store_test.rb b/activerecord/test/cases/store_test.rb
index 978cee9cfb..6a34c55011 100644
--- a/activerecord/test/cases/store_test.rb
+++ b/activerecord/test/cases/store_test.rb
@@ -163,6 +163,22 @@ class StoreTest < ActiveRecord::TestCase
     assert_equal [:width, :height], second_model.stored_attributes[:data]
   end
 
+  test "stored_attributes are tracked per subclass" do
+    first_model = Class.new(ActiveRecord::Base) do
+      store_accessor :data, :color
+    end
+    second_model = Class.new(first_model) do
+      store_accessor :data, :width, :height
+    end
+    third_model = Class.new(first_model) do
+      store_accessor :data, :area, :volume
+    end
+
+    assert_equal [:color], first_model.stored_attributes[:data]
+    assert_equal [:color, :width, :height], second_model.stored_attributes[:data]
+    assert_equal [:color, :area, :volume], third_model.stored_attributes[:data]
+  end
+
   test "YAML coder initializes the store when a Nil value is given" do
     assert_equal({}, @john.params)
   end
-- 
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