Rails 4 - 尽管有白名单，但嵌套参数的参数不允许

Question

我有两个模型user_item和user_item_images。

模式.rb

  create_table "user_item_images", force: :cascade do |t|
    t.integer  "user_item_id"
    t.datetime "created_at"
    t.datetime "updated_at"
    t.string   "picture"
  end
  create_table "user_items", force: :cascade do |t|
    t.integer  "user_id"
    t.integer  "item_id"
    t.integer  "status",          default: 0
    t.boolean  "hide_banner",     default: false
    t.datetime "created_at"
    t.datetime "updated_at"
    t.string   "picture"
    t.string   "declined_reason"
  end

我有一个表单，用户应该在其中提交新user_item。 表单中的唯一字段用于用户可以上传多张图片的图片。 成功后，将为上传的每张图片创建一个新user_item以及一个新user_item_image。

形式

    <%= simple_form_for :user_item, url: user_items_path, html: {multipart: true} do |user_item_builder| %>
      <%= user_item_builder.input :item_id, as: :hidden, input_html: { value: "#{@item.id}" } %>
      <%= user_item_builder.simple_fields_for :user_item_images do |user_item_images_builder| %>
        <%= user_item_images_builder.input :picture, as: :file, label: false, name: "user_item_images[picture][]", input_html: { multiple: true } %>
      <% end %>
    <% end %>

user_item_controller.rb

  def create
    @user_item = current_user.user_items.new(user_item_params)
    raise 'foo'
    if @user_item.save
      params[:user_item][:user_item_images]['picture'].each do |a|
        @user_item_image = @user_item.user_item_images.create!(:picture => a)
      end
      # Sends email to user when item request is created.
      itemMailer.user_item_submission_email(current_user, @user_item.item).deliver_later
      flash[:notice] = "Thank you for your item request!"
    else
      @user_item.errors.full_messages.each do |message|
        flash[:alert] = message
      end
    end
    redirect_to item_path(@user_item.item)
  end
  private 
  def user_item_params
    params.require(:user_item).permit(:item_id, user_item_images_attributes: [:user_item_id, :picture])
  end

user_item.rb

  belongs_to :user
  has_many :user_item_images
  mount_uploader :picture, PictureUploader
  accepts_nested_attributes_for :user_item_images

user_item_image.rb

  mount_uploader :picture, PictureUploader
  belongs_to :user_item

当我提交表单时，我在控制台中得到Unpermitted parameter: user_item_images，但我不知道为什么。

Answer 1

更改以下内容：

    <%= ..., name: "user_item_images[picture][]", ... %>

对此：

    <%= ..., name: "user_item_images_attributes[picture][]", ... %>