Rails上传表单,包含carrierwave和多态关联

Question

我正试图用一种简单的rails应用程序来解决使用多态关联来减少文件管理重复性的问题.我正在使用carrierwave来处理文件上传.这是我到目前为止所拥有的:

应用程序/上传/ file_uploader.rb

class FileUploader < CarrierWave::Uploader::Base
  def store_dir
    "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  end
end

应用程序/模型/ attachment.rb

class Attachment < ActiveRecord::Base
  mount_uploader :file, FileUploader
  belongs_to :attachable, polymorphic: true
end

应用程序/模型/ photo.rb

class Photo < ActiveRecord::Base
  attr_accessible :caption, :attachment
  has_one :attachment, as: :attachable
end

我可以在rails控制台中处理这个问题:

$ rails console
> photo = Photo.new
> attachment = Attachment.new
> attachment.file = File.open('tmp/demo.png')
> photo.attachment = attachment
> photo.save
> photo.attachment
=> #<Attachment id: 3, file: "demo.png", attachable_id: 5, attachable_type: "Photo", created_at: "2013-04-13 16:56:31", updated_at: "2013-04-13 16:56:31">

所以我的问题实际上是在照片控制器中:

ActiveRecord::AssociationTypeMismatch in PhotosController#create
Attachment(#70310274945400) expected, got ActionDispatch::Http::UploadedFile(#70310271741380)`

对此有任何帮助非常感谢.我可能没有最好地掌握多态关联.

UPDATE

根据@ manoj的建议,我编辑了照片表格以嵌套附件:

<%= f.fields_for :attachment do |attachment_f| %>
    <%= attachment_f.file_field :file %>
<% end %>

我在尝试提交表单时遇到此错误:

ActiveRecord::AssociationTypeMismatch (Attachment(#70135925415240) expected, got ActiveSupport::HashWithIndifferentAccess(#70135923190420)):
app/controllers/photos_controller.rb:43:in 'new'
app/controllers/photos_controller.rb:43:in 'create'

Answer 1

post params应该是这样的

params => { "photo" => 
               { :attachment_attribute => 
                  {:file => ActionDispatch::Http::UploadedFile}
               }
          }

但是你的帖子很可能是

params => { "photo" => { :attachment => ActionDispatch::Http::UploadedFile}}

您的视图应包含fields_for以处理模型中的嵌套.您必须为Attachment模型的属性"file"创建一个文件字段

<%=form_for @photo do |photo_f|%>
  ....
  <%=photo_f.fields_for :attachment do |attachment_f|%>
     <%= attachment_f.file_field :file%>
  <%end%>
  ....
<%end%>

UPDATE

<%=photo_f.fields_for :attachment_attributes do |attachment_f|%>

在照片模型中添加这些,

accepts_nested_attributes_for :attachment
attr_accessible ..., :attachment_attributes