Grape formatter feature requested in rails-api#1268

lib/grape-active_model_serializers.rb

@@ -0,0 +1,6 @@
+# To add graoe support, require 'grape-active_model_serializers' in the base of your grape endpoints
+# Then add 'formatter :json, Grape::Formatters::ActiveModelSerializers' to the endpoints
+# Then add 'helpers Grape::Helpers::ActiveModelSerializers' to the endpoints
+require 'active_model_serializers'
+require 'grape/formatters/active_model_serializers'
+require 'grape/helpers/active_model_serializers'

lib/grape/formatters/active_model_serializers.rb

@@ -0,0 +1,17 @@
+# A grape response formatter that can be used as 'formatter :json, Grape::Formatters::ActiveModelSerializers'
+#
+# Serializer options can be passed as a hash from your grape endpoint using env[:active_model_serializer_options],
+# or better yet user the render helper in Grape::Helpers::ActiveModelSerializers
+module Grape
+  module Formatters
+    module ActiveModelSerializers
+      class << self
+        def call(resource, env)
+          serializer_options = {}
+          serializer_options.merge!(env[:active_model_serializer_options]) if env[:active_model_serializer_options]
+          ActiveModel::SerializableResource.new(resource, serializer_options).to_json
+        end
+      end
+    end
+  end
+end

lib/grape/helpers/active_model_serializers.rb

@@ -0,0 +1,16 @@
+# Helpers can be included in your grape endpoint as: helpers Grape::Helpers::ActiveModelSerializers
+module Grape
+  module Helpers
+    module ActiveModelSerializers
+      # A convenience method for passing ActiveModelSerializer serializer options
+      #
+      # Example: To include relationships in the response: render(post, include: ['comments'])
+      #
+      # Example: To include pagination meta data: render(posts, meta: { page: posts.page, total_pages: posts.total_pages })
+      def render(resource, active_model_serializer_options = {})
+        env[:active_model_serializer_options] = active_model_serializer_options
+        resource
+      end
+    end
+  end
+end