Revert "Revert "Merge pull request #16059 from jenncoop/json-serialized-attr""

This reverts commit 6f3c64eeb1dc8288dae49f114aaf619adc7dcb7f.

Conflicts:
	activerecord/CHANGELOG.md

2 files changed, 19 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/attribute_methods/serialization.rb b/activerecord/lib/active_record/attribute_methods/serialization.rb
index 734d94865a..264ce2bdfa 100644
--- a/activerecord/lib/active_record/attribute_methods/serialization.rb
+++ b/activerecord/lib/active_record/attribute_methods/serialization.rb
@@ -37,7 +37,12 @@ module ActiveRecord
         #     serialize :preferences, Hash
         #   end
         def serialize(attr_name, class_name_or_coder = Object)
-          coder = if [:load, :dump].all? { |x| class_name_or_coder.respond_to?(x) }
+          # When ::JSON is used, force it to go through the Active Support JSON encoder
+          # to ensure special objects (e.g. Active Record models) are dumped correctly
+          # using the #as_json hook.
+          coder = if class_name_or_coder == ::JSON
+                    Coders::JSON
+                  elsif [:load, :dump].all? { |x| class_name_or_coder.respond_to?(x) }
                     class_name_or_coder
                   else
                     Coders::YAMLColumn.new(class_name_or_coder)
diff --git a/activerecord/lib/active_record/coders/json.rb b/activerecord/lib/active_record/coders/json.rb
new file mode 100644
index 0000000000..0f60b6dab2
--- /dev/null
+++ b/activerecord/lib/active_record/coders/json.rb
@@ -0,0 +1,13 @@
+module ActiveRecord
+  module Coders # :nodoc:
+    class JSON # :nodoc:
+      def self.dump(obj)
+        ActiveSupport::JSON.encode(obj)
+      end
+
+      def self.load(json)
+        ActiveSupport::JSON.decode(json)
+      end
+    end
+  end
+end