Fix inheritance of stored_attributes (fixes rails#14672)

[Brad Bennett, Jessica Yao, & Lakshmi Parthasarathy]

Author: jyao6

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.

activerecord/lib/active_record/store.rb

@@ -66,8 +66,9 @@ module Store
     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 @@ def store_accessor(store_attribute, *keys)
 
         # 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 @@ def _store_accessors_module
           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

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