ActiveRecord::UnknownAttributeError

Question

我正在尝试创建带有一些字段的酒店，其中一个字段是照片，我想使用带有carrierwave 和nested_form 的多个文件上传。我找到了这个article 并有一些结果。

当我在 /hotels/new 时，填写字段，选择照片 然后按提交，在 HotelsController#create unknown attribute: attachable_type 中得到 ActiveRecord::UnknownAttributeError。 控制台

Started POST "/hotels" for 127.0.0.1 at 2013-09-27 17:35:18 +0300
Processing by HotelsController#create as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"+1T2tuygSnj8unOKkXkRWI4L7KvDE
9PPHrqvag7KmIQ=", "hotel"=>{"title"=>"dsa", "address"=>"asd", "star_rating"=>"2"
, "breakfast"=>"Not include", "price_for_room"=>"sadas", "room_description"=>"Gr
eat room", "attachments_attributes"=>{"1380289954031"=>{"file"=>#<ActionDispatch
::Http::UploadedFile:0xa5d546c @original_filename="11374.jpg", @content_type="im
age/jpeg", @headers="Content-Disposition: form-data; name=\"hotel[attachments_at
tributes][1380289954031][file]\"; filename=\"11374.jpg\"\r\nContent-Type: image/
jpeg\r\n", @tempfile=#<File:/tmp/RackMultipart20130927-7077-50zkol>>, "_destroy"
=>"false"}, "1380289972216"=>{"file"=>#<ActionDispatch::Http::UploadedFile:0xa5d
53a4 @original_filename="357175.jpg", @content_type="image/jpeg", @headers="Cont
ent-Disposition: form-data; name=\"hotel[attachments_attributes][1380289972216][
file]\"; filename=\"357175.jpg\"\r\nContent-Type: image/jpeg\r\n", @tempfile=#<F
ile:/tmp/RackMultipart20130927-7077-dlkmwk>>, "_destroy"=>"false"}}}, "commit"=>
"Done"}
Completed 500 Internal Server Error in 109ms

ActiveRecord::UnknownAttributeError (unknown attribute: attachable_type):
  app/controllers/hotels_controller.rb:15:in `new'
  app/controllers/hotels_controller.rb:15:in `create' 
...

样板酒店.rb

class Hotel < ActiveRecord::Base
  attr_accessible :address, :breakfast, :price_for_room, :room_description,
                :star_rating, :title, :attachments_attributes

  has_many :attachments, :as => :attachable
  accepts_nested_attributes_for :attachments
end

模型附件.rb

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

hotels_controller.rb

...
      def new
        @hotel = Hotel.new
      end
      def create
        @hotel = Hotel.new(params[:hotel])
        if @hotel.save
          redirect_to hotels_path, notice: "Nice, you added new hotel " + @hotel.title
        else
          render "new"
        end  
      end

_form.rb

<%= nested_form_for @hotel, :html => {:multipart => true}  do |f| %>
  ...
  <%= f.fields_for :attachments do |attachment_form|%>    
    <%= attachment_form.label :file %>
    <%= attachment_form.file_field :file %>
    <%= attachment_form.link_to_remove "Remove this photo" %>
  <% end %>
  <%= f.link_to_add "Add photo", :attachments %>
  <%= f.submit 'Done', class: 'btn btn-success' %>
<% end %>

有什么想法吗？我在这里做错了什么？

Answer 1

ActiveRecord::UnknownAttributeError 表示您在数据库中缺少一个字段。看起来您在设置多态关系时错过了一个字段，或者您忘记运行迁移。

另请参阅：http://guides.rubyonrails.org/association_basics.html#polymorphic-associations

Answer 2

尝试创建文件名 app/uploaders/photo_uploader.rb

# encoding: utf-8
class PhotoUploader < CarrierWave::Uploader::Base
  # Include RMagick or MiniMagick support:
  include CarrierWave::RMagick
  # include CarrierWave::MiniMagick
  include Sprockets::Helpers::RailsHelper
  include Sprockets::Helpers::IsolatedHelper
  include CarrierWave::MimeTypes
  process :set_content_type
  def store_dir
    "uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
  end
  def extension_white_list
     %w(jpg jpeg gif png)
  end
# process :resize_to_fit => [800, 800]

  version :thumb do
    process :resize_to_limit => [50, 50]
  end
end

然后在你的模型中添加

mount_uploader :image, PhotoUploader
mount_uploader :image2, PhotoUploader

你可能有这个

/config/initializers/carrierwave.rb

CarrierWave.configure do |config|
  config.storage = :fog
  config.fog_credentials = {
    :provider => 'AWS',
    :aws_access_key_id => ENV['CARRIER_WAVE_ACCESS_KEY'],
    :aws_secret_access_key => ENV['CARRIER_WAVE_SECRET_ACCESS_KEY']
  }
  config.cache_dir = "#{Rails.root}/tmp/uploads"
  config.fog_directory = ENV['CARRIER_WAVE_BUCKET']
  config.fog_attributes = { 'Cache-Control'=>'max-age=315576000' }
  #config.fog_public = false # optional, defaults to true
end