Allow for the implicit use of ArraySerializer when :each_serializer is specified.

README.md

@@ -107,7 +107,12 @@ If you wish to use a serializer other than the default, you can explicitly pass
 #### 2. For an array resource:
 
 ```ruby
-  render json: @posts, serializer: PaginatedSerializer, each_serializer: PostPreviewSerializer
+# Use the default `ArraySerializer`, which will use `each_serializer` to
+# serialize each element
+render json: @posts, each_serializer: PostPreviewSerializer
+
+# Or, you can explicitly provide the collection serializer as well
+render json: @posts, serializer: PaginatedSerializer, each_serializer: PostPreviewSerializer
 ```
 
 ## Installation

lib/action_controller/serialization.rb

@@ -9,12 +9,14 @@ module ActionController
     ADAPTER_OPTION_KEYS = [:include, :root]
 
     def get_serializer(resource, options)
-      @_serializer ||= if (serializer = options.delete :serializer)
-        options[:serializer] = options.delete :each_serializer
-        serializer
-      else
-        ActiveModel::Serializer.serializer_for(resource)
+      @_serializer ||= options.delete(:serializer)
+      @_serializer ||= ActiveModel::Serializer.serializer_for(resource)
+
+      if options.key?(:each_serializer)
+        options[:serializer] = options.delete(:each_serializer)
       end
+
+      @_serializer
     end
 
     [:_render_option_json, :_render_with_renderer_json].each do |renderer_method|

test/action_controller/explicit_serializer_test.rb

@@ -24,6 +24,19 @@ module ActionController
                  serializer: PaginatedSerializer,
                  each_serializer: ProfilePreviewSerializer
         end
+
+        def render_array_using_implicit_serializer
+          array = [
+            Profile.new(name: 'Name 1',
+                        description: 'Description 1',
+                        comments: 'Comments 1'),
+            Profile.new(name: 'Name 2',
+                        description: 'Description 2',
+                        comments: 'Comments 2')
+          ]
+          render json: array,
+                 each_serializer: ProfilePreviewSerializer
+        end
       end
 
       tests MyController
@@ -48,6 +61,18 @@ module ActionController
 
         assert_equal expected.to_json, @response.body
       end
+
+      def test_render_array_using_explicit_serializer
+        get :render_array_using_implicit_serializer
+        assert_equal 'application/json', @response.content_type
+
+        expected = [
+          { 'name' => 'Name 1' },
+          { 'name' => 'Name 2' }
+        ]
+        assert_equal expected.to_json, @response.body
+      end
+
     end
   end
 end