ruby on rails - How to flatten the json produced by Rabl -

i'm starting out rabl , trying include parent attribute @ same level child.

this have far..

class usertag < activerecord::base     belongs_to :tag     attr_accessible :user_id, :tag_id end

my index.json.rabl

object @usertag attributes :id child :tag   attributes :name end

produces

[{"usertag":{"id":1,"tag":{"name":"dolor et non."}}},

how flatten child node in template produces

[{"usertag":{"id":1,"name":"dolor et non."

thanks!

HR