Fix #876 - include meta when using json adapter with custom root

lib/active_model/serializer/adapter.rb

@@ -75,7 +75,7 @@ def meta_key
       end
 
       def root
-        serializer.json_key
+        @options.fetch(:root, serializer.json_key)
       end
 
       def include_meta(json)

lib/active_model/serializer/adapter/json.rb

@@ -37,9 +37,7 @@ def serializable_hash(options = {})
             @result = @core.merge @hash
           end
 
-          if root = options.fetch(:root, serializer.json_key)
-            @result = { root => @result }
-          end
+          @result = { root => @result } if root
           @result
         end
       end
@@ -49,4 +47,4 @@ def fragment_cache(cached_hash, non_cached_hash)
       end
     end
   end
-end
+end

test/action_controller/serialization_test.rb

@@ -14,6 +14,11 @@ def render_using_custom_root
           render json: @profile, root: "custom_root"
         end
 
+        def render_using_custom_root_and_meta
+          @profile = Profile.new({ name: 'Name 1', description: 'Description 1', comments: 'Comments 1' })
+          render json: @profile, root: "custom_root", meta: { total: 10 }
+        end
+
         def render_using_default_adapter_root
           with_adapter ActiveModel::Serializer::Adapter::JsonApi do
             # JSON-API adapter sets root by default
@@ -161,6 +166,13 @@ def test_render_using_custom_root
         assert_equal '{"custom_root":{"name":"Name 1","description":"Description 1"}}', @response.body
       end
 
+      def test_render_using_custom_root_and_meta
+        get :render_using_custom_root_and_meta
+
+        assert_equal 'application/json', @response.content_type
+        assert_equal '{"custom_root":{"name":"Name 1","description":"Description 1"},"meta":{"total":10}}', @response.body
+      end
+
       def test_render_using_default_root
         get :render_using_default_adapter_root