rails json exclude nested attribute
render :json => @booking, :include => [:paypal,
:boat_people,
:boat => {:only => :name, :include => {:port => {:only => :name, :include => {:city => {:only => :name, :include => {:country => {:only => :name}}}}},
:boat_model => {:only => :name, :include => {:boat_type => {:only => :name}}}}}]