def batch_update
  quantity_caritem=params[:items]
  quantity_caritem.size.times.each do |i|
    caritem_id=quantity_caritem["#{i}"][:caritem_id]
   quantity = quantity_caritem["#{i}"][:quantity]
  @caritem = Caritem.find_by(:id=>caritem_id)
  @caritem.update(:quantity=>quantity)
  end
  @caritems = current_user.caritems
 render_success @caritems, :include=>{
     :product=>{
         :include=>[:product_images, :master],
         :method=>[:has_variants],
         :except=>[:description]
     },
     :variant=>{
         :methods=>[:options_key, :options_label]
     }
 }, :methods=>[:price]
end

这是控制台记录传来的参数
parameters = {"items"=>{"0"=>{"caritem_id"=>"24", "quantity"=>"4"}, "1"=>{"caritem_id"=>"25", "quantity"=>"6"}}, "controller"=>"api/caritems", "action"=>"batch_update"} 
但是 debug模式下quantity_caritem为nil
请问下各位是哪里错了!
谢谢!