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我正在开发一个名为 Chapter 的模型，它允许用户使用carrierwave 上传多个图像（+ 一个单独的缩略图）。我创建了一个名为 Attachment 的多态模型来安装上传器。

章节

class Chapter < ActiveRecord::Base
  attr_accessible :title, :uploader_comment, :book_id, :attachments_attributes

  has_many :comments, as: :commentable
  has_many :attachments, as: :attachable

  accepts_nested_attributes_for :attachments

  belongs_to :book
  belongs_to :user

  validates :title, presence: true, length: {maximum: 60}
  validates :book_id, presence: true
  validates :uploader_comment, length: {maximum: 150}
  validates :user_id, presence: true 
  validates :attachments, presence: true
end

附件

class Attachment < ActiveRecord::Base
    attr_accessible :chapter_image, :chapter_thumb

    belongs_to :attachable, polymorphic: true

    mount_uploader :chapter_image, ChapterImageUploader
    mount_uploader :chapter_thumb, ChapterThumbnailUploader

    validates_presence_of :chapter_image

end

写完上述代码后，我尝试提交表单，但最终得到 “未定义的方法 `chapter_image_will_change!' 为...”错误。经过一番搜索，我在另一篇文章中看到我需要运行一些迁移才能摆脱错误。所以我做了以下。

rails g migration AddAttachmentToChapters 
  chapter_image:string chapter_thumb:string

bundle exec rake db:migrate

但错误仍然存​​在。我将包括我的视图页面代码，以防万一它会有所帮助。

新的.html.erb

<div class = "row">
  <div class = "span6 offset3">

    <%= simple_nested_form_for @chapter, html: {multipart: true}, 
        defaults: {required: false} do |f| %>

      <%= render 'shared/error_messages', object: @chapter %>

      <%= f.association :book, collection: current_user.books.all, 
                        tag: :book_id, include_blank: false %>

      <%= f.input :title, label: 'Chapter title' %>

      <%= f.input :uploader_comment %>

      <div class = "control-label">
        Image file upload
      </div>
      <%= f.simple_fields_for :attachments do |attachment_form| %>
        <%= attachment_form.file_field :chapter_image %>
        <%= attachment_form.link_to_remove 'Remove' %>
      <% end %>
      <%= f.link_to_add 'Add image', :attachments %>
      <span class="hint_end">Acceptable file formats: JPG, JPEG, GIF, PNG</span>

      <div class = "control-label">
        Thumbnail upload
      </div>
      <%= f.file_field :chapter_thumb %>
      <span class="hint_end">Acceptable file formats: JPG, JPEG, GIF, PNG</span>

      <%= f.submit "Upload chapter" %>

    <% end %>
  </div>
</div>

欢迎任何建议/帮助！

4

1 回答 1

3

您需要将缺少的列添加到Attachment模型中，而不是Chapter：

rails g migration AddImageToAttachments chapter_image:string chapter_thumb:string
于 2013-03-11T05:55:14.640 回答