Desired output.json

    { "activities": 
        [ 
          {
            "id": 1,
            "title": "likes your app x",
            "actor": {
               "type": "user",
               "id": 3
            },
            "verbs": [
              "post"
            ],
            "object": {
              "type": "comment",
              "id": 1,
              "content": "Vel voluptate aliquid et doloribus sint eum ad sequi."
            },
            "indirect_object": {
              "type": "app",
              "id": 1
            }
          }
        ]
      }

tokamak-view.rb

collection(@activities) do |collection|
  collection.members do |member, activity|
    member.values { |values|
      values.id           activity.id
      values.title        activity.title

      # ACTOR
      values.actor :type => activity.actor_type.downcase, :id => activity.actor_id

      # VERB
      values.verbs  activity.verbs

      # OBJECT
      object_hash = { :type => activity.object_type.downcase, :id => activity.object_id } 
      object_hash[:content] = activity.object.content if activity.object_content?

      values.object object_hash

      # Indirect OBJECT
      if activity.indirect_object
        indirect_object_hash = { :type => activity.indirect_object_type.downcase, :id => activity.indirect_object_id} 

        values.indirect_object indirect_object_hash
      end

    }
  end
  

end