Carrierwave only upload image when update action when using Rails 4 and nested form -

my model:

class product < activerecord::base   has_many :product_images, dependent: :destroy   accepts_nested_attributes_for :product_images, :reject_if => lambda { |p| p['image'].blank? }, :allow_destroy => true end   class productimage < activerecord::base   belongs_to :product   mount_uploader :image, productimageuploader   validates_presence_of :image end 

my controller:

  def create     @product = product.new(permitted_params.product)     if @product.save         redirect_to edit_admin_product_path(@product), notice: "success"     else       render :new     end   end    def update     @product = product.find(params[:id])     if @product.update_attributes(permitted_params.product)       redirect_to edit_admin_product_path(@product), notice: "success"     else       render :edit     end   end 

permitted_params:

class permittedparams < struct.new(:params)   def product     params.require(:product).permit(*product_attrs)   end    def product_attrs     [:name, :content, :stock, :list_price, :selling_price, :bonus, :is_added,      product_images_attributes: [:id, :image, :_destroy] ]   end end 

and parameters passed:

parameters: {"utf8"=>"✓", "authenticity_token"=>"eqweq1231sda+3t0131643guxybt75x6nqn1ng=", "product"=>{"name"=>"weqwe", "content"=>"qweq", "product_images_attributes"=>{"0"=>{"image"=>"1069218_513152615405563_1187314087_n.jpg", "_destroy"=>""}}, "stock"=>"", "list_price"=>"", "selling_price"=>"123", "bonus"=>""}, "commit"=>"submit"} 

obviously image pass params. when create product rollback alarm image empty(validate presence image in productimage model).

if delete validation create product. can upload images in update action. have totally no idea what's problem! please help. q_q