Adds support for custom serializers

This commit implements the 0.9.x style of 
explicitly passing a serializer to a JSON render
call in a controller as an option to `render :json`

Additionally, this commit adds Yard for docs

Gemfile

@@ -4,6 +4,7 @@ source 'https://rubygems.org'
 gemspec
 
 gem "minitest"
+gem "yard"
 
 version = ENV["RAILS_VERSION"] || "4.1"
 

lib/action_controller/serialization.rb

@@ -5,13 +5,32 @@ module Serialization
     extend ActiveSupport::Concern
 
     include ActionController::Renderers
+
+    # Overrides ActiveController's JSON serialization
+    # strategy with our own approach. By default, uses
+    # the NullAdapter and a serializer matching the
+    # resource passed by the controller.
+    #
+    # @option options [Class] :serializer A serializer 
+    # @option options [Class] :adapter An adapter
+    #
+    # @api private
 
     def _render_option_json(resource, options)
-      serializer = ActiveModel::Serializer.serializer_for(resource)
+      serializer = if options[:serializer]
+        options[:serializer]
+      else
+        ActiveModel::Serializer.serializer_for(resource)
+      end
 
       if serializer
         object = serializer.new(resource)
-        adapter = ActiveModel::Serializer.default_adapter.new(object)
+
+        adapter = if options[:adapter]
+          options[:adapter]
+        else
+          ActiveModel::Serializer.default_adapter.new(object)
+        end.new(object)
 
         super(adapter, options)
       else

lib/active_model/serializer.rb

@@ -12,7 +12,17 @@ def default_adapter
     def self.inherited(base)
       base._attributes = []
     end
-
+
+    # Define the list of attributes to serialize
+    #
+    # For each symbol passed, check to see if the model
+    # has a matching method defined. Otherwise, define a 
+    # new method which calls `read_attribute_for_serialization`
+    # 
+    # @param [Symbol] attrs
+    #   the attr to define a new method for
+    #
+    # @api public
     def self.attributes(*attrs)
       @_attributes.concat attrs
 
@@ -23,7 +33,13 @@ def self.attributes(*attrs)
       end
     end
 
-    if RUBY_VERSION >= '2.0'
+    if RUBY_VERSION >= '2.0' 
+    # Returns constantized serial class, for a given resource
+    #
+    # @param [Object] resource
+    #   the resource to find a matching serializer for
+    #
+    # @api public
       def self.serializer_for(resource)
         if resource.respond_to?(:to_ary)
           ArraySerializer
@@ -43,14 +59,17 @@ def self.serializer_for(resource)
           "#{resource.class.name}Serializer".safe_constantize
         end
       end
-    end
+    end 
 
     attr_accessor :object
-
+    
     def initialize(object)
       @object = object
     end
 
+    # Returns a hash of attributes defined by `self.attributes(*attrs)`
+    # 
+    # @api public
     def attributes
       self.class._attributes.dup.each_with_object({}) do |name, hash|
         hash[name] = send(name)

test/action_controller/serialization_test.rb

@@ -20,6 +20,27 @@ def test_render_using_implicit_serializer
         assert_equal '{"name":"Name 1","description":"Description 1"}', @response.body
       end
     end
+
+    class ExplicitSerializerTest < ActionController::TestCase
+      class ExplicitProfileSerializer < ActiveModel::Serializer
+        attributes :name
+      end
+
+      class MyController < ActionController::Base
+        def render_using_explicit_serializer
+          render json: Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' }), serializer: ExplicitProfileSerializer 
+        end
+      end
+
+      tests MyController
+
+      def test_render_using_explicit_serializer
+        get :render_using_explicit_serializer
+
+        assert_equal 'application/json', @response.content_type
+        assert_equal '{"name":"Name 1"}', @response.body
+      end
+    end
   end
 end