Fields_for每次我无限制地建造

Question

我有2个型号，服务和子服务。

class Service < ActiveRecord::Base
    mount_uploader :teaser, TeaserUploader
    has_many :subservices
    accepts_nested_attributes_for :subservices, allow_destroy: true
end

class Subservice < ActiveRecord::Base
    mount_uploader :subicon, SubiconUploader
    belongs_to :service, dependent: :destroy
    validates_presence_of :service
end

我希望每个服务都有许多子服务，我通过这个表单添加：

<%= simple_form_for @service do |f| %>
  <%= f.input :name  %>

   <%= f.fields_for :subservices do |builder| %>
     <%= builder.input :name, label: "Nombre Servicio", class: "form-control" %>
     <%= builder.input :description, label: "Descripción del servicio" %>
     <%= builder.input :subicon, label: "Icono" %>
  <% end %>
  <%= f.button :submit %>
<% end %>

它工作正常，但每次我编辑一个新的子服务时，它都会被复制而不是保存旧的子服务。 它为表单添加了一个新的子服务，而不仅仅是编辑实际的子服务。

  # GET /services/1/edit
  def edit
    @service = Service.find(params[:id])
    @service.subservices.build 
  end

谢谢！