Allow overriding the adapter with render option

Make it easy to use multiple adapters in an app.

use "adapter: false" to not use ams

make a test override config.adapter

lib/action_controller/serialization.rb

@@ -6,29 +6,32 @@ module Serialization
 
     include ActionController::Renderers
 
-    ADAPTER_OPTION_KEYS = [:include, :root]
+    ADAPTER_OPTION_KEYS = [:include, :root, :adapter]
 
-    def get_serializer(resource, options)
-      @_serializer ||= options.delete(:serializer)
+    def get_serializer(resource)
+      @_serializer ||= @_serializer_opts.delete(:serializer)
       @_serializer ||= ActiveModel::Serializer.serializer_for(resource)
 
-      if options.key?(:each_serializer)
-        options[:serializer] = options.delete(:each_serializer)
+      if @_serializer_opts.key?(:each_serializer)
+        @_serializer_opts[:serializer] = @_serializer_opts.delete(:each_serializer)
       end
 
       @_serializer
     end
 
+    def use_adapter?
+      !(@_adapter_opts.key?(:adapter) && !@_adapter_opts[:adapter])
+    end
+
     [:_render_option_json, :_render_with_renderer_json].each do |renderer_method|
       define_method renderer_method do |resource, options|
-
-        adapter_opts, serializer_opts =
+        @_adapter_opts, @_serializer_opts =
           options.partition { |k, _| ADAPTER_OPTION_KEYS.include? k }.map { |h| Hash[h] }
 
-        if (serializer = get_serializer(resource, serializer_opts))
+        if use_adapter? && (serializer = get_serializer(resource))
           # omg hax
-          object = serializer.new(resource, serializer_opts)
-          adapter = ActiveModel::Serializer.adapter.new(object, adapter_opts)
+          object = serializer.new(resource, @_serializer_opts)
+          adapter = ActiveModel::Serializer::Adapter.create(object, @_adapter_opts)
           super(adapter, options)
         else
           super(resource, options)

lib/active_model/serializer.rb

@@ -90,8 +90,7 @@ def self.serializer_for(resource)
     def self.adapter
       adapter_class = case config.adapter
       when Symbol
-        class_name = "ActiveModel::Serializer::Adapter::#{config.adapter.to_s.classify}"
-        class_name.safe_constantize
+        ActiveModel::Serializer::Adapter.adapter_class(config.adapter)
       when Class
         config.adapter
       end

lib/active_model/serializer/adapter.rb

@@ -20,6 +20,16 @@ def serializable_hash(options = {})
       def as_json(options = {})
         serializable_hash(options)
       end
+
+      def self.create(resource, options = {})
+        override = options.delete(:adapter)
+        klass = override ? adapter_class(override) : ActiveModel::Serializer.adapter
+        klass.new(resource, options)
+      end
+
+      def self.adapter_class(adapter)
+        "ActiveModel::Serializer::Adapter::#{adapter.to_s.classify}".safe_constantize
+      end
     end
   end
 end

test/action_controller/adapter_selector_test.rb

@@ -0,0 +1,41 @@
+require 'test_helper'
+
+module ActionController
+  module Serialization
+    class AdapterSelectorTest < ActionController::TestCase
+      class MyController < ActionController::Base
+        def render_using_default_adapter
+          @profile = Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' })
+          render json: @profile
+        end
+
+        def render_using_adapter_override
+          @profile = Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' })
+          render json: @profile, adapter: :json_api
+        end
+
+        def render_skipping_adapter
+          @profile = Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' })
+          render json: @profile, adapter: false
+        end
+      end
+
+      tests MyController
+
+      def test_render_using_default_adapter
+        get :render_using_default_adapter
+        assert_equal '{"name":"Name 1","description":"Description 1"}', response.body
+      end
+
+      def test_render_using_adapter_override
+        get :render_using_adapter_override
+        assert_equal '{"profiles":{"name":"Name 1","description":"Description 1"}}', response.body
+      end
+
+      def test_render_skipping_adapter
+        get :render_skipping_adapter
+        assert_equal '{"attributes":{"name":"Name 1","description":"Description 1","comments":"Comments 1"}}', response.body
+      end
+    end
+  end
+end

test/action_controller/json_api_linked_test.rb

@@ -28,54 +28,34 @@ def setup_post
           @second_comment.author = nil
         end
 
-        def with_json_api_adapter
-          old_adapter = ActiveModel::Serializer.config.adapter
-          ActiveModel::Serializer.config.adapter = :json_api
-          yield
-        ensure
-          ActiveModel::Serializer.config.adapter = old_adapter
-        end
-
         def render_resource_without_include
-          with_json_api_adapter do
-            setup_post
-            render json: @post
-          end
+          setup_post
+          render json: @post, adapter: :json_api
         end
 
         def render_resource_with_include
-          with_json_api_adapter do
-            setup_post
-            render json: @post, include: 'author'
-          end
+          setup_post
+          render json: @post, include: 'author', adapter: :json_api
         end
 
         def render_resource_with_nested_include
-          with_json_api_adapter do
-            setup_post
-            render json: @post, include: 'comments.author'
-          end
+          setup_post
+          render json: @post, include: 'comments.author', adapter: :json_api
         end
 
         def render_resource_with_nested_has_many_include
-          with_json_api_adapter do
-            setup_post
-            render json: @post, include: 'author,author.roles'
-          end
+          setup_post
+          render json: @post, include: 'author,author.roles', adapter: :json_api
         end
 
         def render_collection_without_include
-          with_json_api_adapter do
-            setup_post
-            render json: [@post]
-          end
+          setup_post
+          render json: [@post], adapter: :json_api
         end
 
         def render_collection_with_include
-          with_json_api_adapter do
-            setup_post
-            render json: [@post], include: 'author,comments'
-          end
+          setup_post
+          render json: [@post], include: 'author,comments', adapter: :json_api
         end
       end
 

test/action_controller/serialization_test.rb

@@ -25,13 +25,9 @@ def render_using_default_adapter_root
         end
 
         def render_using_custom_root_in_adapter_with_a_default
-          old_adapter = ActiveModel::Serializer.config.adapter
           # JSON-API adapter sets root by default
-          ActiveModel::Serializer.config.adapter = ActiveModel::Serializer::Adapter::JsonApi
           @profile = Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' })
-          render json: @profile, root: "profile"
-        ensure
-          ActiveModel::Serializer.config.adapter = old_adapter
+          render json: @profile, root: "profile", adapter: :json_api
         end
 
         def render_array_using_implicit_serializer

test/adapter_test.rb

@@ -18,6 +18,26 @@ def test_serializable_hash_is_abstract_method
       def test_serializer
         assert_equal @serializer, @adapter.serializer
       end
+
+      def test_adapter_class_for_known_adapter
+        klass = ActiveModel::Serializer::Adapter.adapter_class(:json_api)
+        assert_equal ActiveModel::Serializer::Adapter::JsonApi, klass
+      end
+
+      def test_adapter_class_for_unknown_adapter
+        klass = ActiveModel::Serializer::Adapter.adapter_class(:json_simple)
+        assert_nil klass
+      end
+
+      def test_create_adapter
+        adapter = ActiveModel::Serializer::Adapter.create(@serializer)
+        assert_equal ActiveModel::Serializer::Adapter::Json, adapter.class
+      end
+
+      def test_create_adapter_with_override
+        adapter = ActiveModel::Serializer::Adapter.create(@serializer, { adapter: :json_api})
+        assert_equal ActiveModel::Serializer::Adapter::JsonApi, adapter.class
+      end
     end
   end
 end

test/serializers/configuration_test.rb

@@ -7,7 +7,7 @@ def test_array_serializer
         assert_equal ActiveModel::Serializer::ArraySerializer, ActiveModel::Serializer.config.array_serializer
       end
 
-      def test_adapter
+      def test_default_adapter
         assert_equal :json, ActiveModel::Serializer.config.adapter
       end
     end