4 files changed, 37 insertions, 11 deletions
diff --git a/actionpack/lib/action_controller.rb b/actionpack/lib/action_controller.rb
index f4eaa2fd1b..3829e60bb0 100644
--- a/actionpack/lib/action_controller.rb
+++ b/actionpack/lib/action_controller.rb
@@ -31,6 +31,7 @@ module ActionController
     autoload :RequestForgeryProtection
     autoload :Rescue
     autoload :Responder
+    autoload :Serialization
     autoload :SessionManagement
     autoload :Streaming
     autoload :Testing
diff --git a/actionpack/lib/action_controller/base.rb b/actionpack/lib/action_controller/base.rb
index 98bfe72fef..cfb9cf5e6e 100644
--- a/actionpack/lib/action_controller/base.rb
+++ b/actionpack/lib/action_controller/base.rb
@@ -190,6 +190,7 @@ module ActionController
       Redirecting,
       Rendering,
       Renderers::All,
+      Serialization,
       ConditionalGet,
       RackDelegation,
       SessionManagement,
diff --git a/actionpack/lib/action_controller/metal/renderers.rb b/actionpack/lib/action_controller/metal/renderers.rb
index 0ad9dbeda9..6e9ce450ac 100644
--- a/actionpack/lib/action_controller/metal/renderers.rb
+++ b/actionpack/lib/action_controller/metal/renderers.rb
@@ -1,5 +1,6 @@
 require 'active_support/core_ext/class/attribute'
 require 'active_support/core_ext/object/blank'
+require 'set'
 
 module ActionController
   # See <tt>Renderers.add</tt>
@@ -12,16 +13,13 @@ module ActionController
 
     included do
       class_attribute :_renderers
-      self._renderers = {}.freeze
+      self._renderers = Set.new.freeze
     end
 
     module ClassMethods
       def use_renderers(*args)
-        new = _renderers.dup
-        args.each do |key|
-          new[key] = RENDERERS[key]
-        end
-        self._renderers = new.freeze
+        renderers = _renderers + args
+        self._renderers = renderers.freeze
       end
       alias use_renderer use_renderers
     end
@@ -31,10 +29,10 @@ module ActionController
     end
 
     def _handle_render_options(options)
-      _renderers.each do |name, value|
-        if options.key?(name.to_sym)
+      _renderers.each do |name|
+        if options.key?(name)
           _process_options(options)
-          return send("_render_option_#{name}", options.delete(name.to_sym), options)
+          return send("_render_option_#{name}", options.delete(name), options)
         end
       end
       nil
@@ -42,7 +40,7 @@ module ActionController
 
     # Hash of available renderers, mapping a renderer name to its proc.
     # Default keys are :json, :js, :xml.
-    RENDERERS = {}
+    RENDERERS = Set.new
 
     # Adds a new renderer to call within controller actions.
     # A renderer is invoked by passing its name as an option to
@@ -79,7 +77,7 @@ module ActionController
     # <tt>ActionController::MimeResponds#respond_with</tt>
     def self.add(key, &block)
       define_method("_render_option_#{key}", &block)
-      RENDERERS[key] = block
+      RENDERERS << key.to_sym
     end
 
     module All
diff --git a/actionpack/lib/action_controller/metal/serialization.rb b/actionpack/lib/action_controller/metal/serialization.rb
new file mode 100644
index 0000000000..9bb665a9ae
--- /dev/null
+++ b/actionpack/lib/action_controller/metal/serialization.rb
@@ -0,0 +1,26 @@
+module ActionController
+  module Serialization
+    extend ActiveSupport::Concern
+
+    include ActionController::Renderers
+
+    included do
+      class_attribute :_serialization_scope
+    end
+
+    def serialization_scope
+      send(_serialization_scope)
+    end
+
+    def _render_option_json(json, options)
+      json = json.active_model_serializer.new(json, serialization_scope) if json.respond_to?(:active_model_serializer)
+      super
+    end
+
+    module ClassMethods
+      def serialization_scope(scope)
+        self._serialization_scope = scope
+      end
+    end
+  end
+end