Merge pull request rails#46090 from nvasilevski/do-not-write-to-store-unchanged-value

Do not write unchanged value to ActiveRecord::Store

Author: rafaelfranca

activerecord/lib/active_record/store.rb

@@ -225,7 +225,7 @@ def self.read(object, attribute, key)
 
         def self.write(object, attribute, key, value)
           prepare(object, attribute)
-          object.public_send(attribute)[key] = value
+          object.public_send(attribute)[key] = value if value != read(object, attribute, key)
         end
 
         def self.prepare(object, attribute)

activerecord/test/cases/store_test.rb

@@ -31,6 +31,12 @@ class StoreTest < ActiveRecord::TestCase
     assert_equal "37signals.com", @john.homepage
   end
 
+  test "writing store attributes does not update unchanged value" do
+    admin_user = Admin::User.new(homepage: nil)
+    admin_user.homepage = nil
+    assert_equal({}, admin_user.settings)
+  end
+
   test "reading store attributes through accessors with prefix" do
     assert_equal "Quinn", @john.parent_name
     assert_nil @john.parent_birthday