json - Rails as_json include parent object? -

hello i'm trying use as_json output parent object include. here code :

photo.as_json(:include => [:comments, :likes]) 

this code works, 1 doesn't :

photo.as_json(:include => [:comments, :likes, :user]) 

i error :

nomethoderror: undefined method `macro' nil:nilclass 

any 1 ? :)

try

user = user.find(1)     user.as_json(:include => {:photos => {:include => [:comments, :likes]}})