1 files changed, 71 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/type/serialized.rb b/activerecord/lib/active_record/type/serialized.rb
new file mode 100644
index 0000000000..0a2f6cb9fb
--- /dev/null
+++ b/activerecord/lib/active_record/type/serialized.rb
@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+module ActiveRecord
+  module Type
+    class Serialized < DelegateClass(ActiveModel::Type::Value) # :nodoc:
+      undef to_yaml if method_defined?(:to_yaml)
+
+      include ActiveModel::Type::Helpers::Mutable
+
+      attr_reader :subtype, :coder
+
+      def initialize(subtype, coder)
+        @subtype = subtype
+        @coder = coder
+        super(subtype)
+      end
+
+      def deserialize(value)
+        if default_value?(value)
+          value
+        else
+          coder.load(super)
+        end
+      end
+
+      def serialize(value)
+        return if value.nil?
+        unless default_value?(value)
+          super coder.dump(value)
+        end
+      end
+
+      def inspect
+        Kernel.instance_method(:inspect).bind(self).call
+      end
+
+      def changed_in_place?(raw_old_value, value)
+        return false if value.nil?
+        raw_new_value = encoded(value)
+        raw_old_value.nil? != raw_new_value.nil? ||
+          subtype.changed_in_place?(raw_old_value, raw_new_value)
+      end
+
+      def accessor
+        ActiveRecord::Store::IndifferentHashAccessor
+      end
+
+      def assert_valid_value(value)
+        if coder.respond_to?(:assert_valid_value)
+          coder.assert_valid_value(value, action: "serialize")
+        end
+      end
+
+      def force_equality?(value)
+        coder.respond_to?(:object_class) && value.is_a?(coder.object_class)
+      end
+
+      private
+
+        def default_value?(value)
+          value == coder.load(nil)
+        end
+
+        def encoded(value)
+          unless default_value?(value)
+            coder.dump(value)
+          end
+        end
+    end
+  end
+end