error in variale name

app/models/product.rb

@@ -353,7 +353,7 @@ class Product < ActiveRecord::Base
     attributes = ""
     unless attributes_json.nil?
       attributes_to_hash.each do |_attr_, value|
-        attributes = attributes.blank? ? values.to_s : attributes.to_s + value.to_s
+        attributes = attributes.blank? ? value.to_s : attributes.to_s + value.to_s
       end
     end
     attributes