在 rails 应用程序中使用回形针时出错

问题描述

目前我尝试用回形针替换attachment_fu文件上传插件.

At the moment I try to replace attachment_fu fileuploading plugin with paperclip.

但上传时出现一些错误:

But there are some errors while uploading:

我的控制器如下所示:

def create
add_breadcrumb 'breadcrumb.upload_file', {:action => :new}

puts "BLUBBBBBBBBBBBBBBBBBBBBBBBBBBB"
puts params[:upload]

    @upload = Upload.create(params[:upload])
    @upload.lecturer_id = current_user.id
    if @upload.save
        flash[:notice] = I18n.t("flash.saved")
        redirect_to :action => :index
    else
        render :action => :new
    end
end

我的模型是这样的:

puts has_attached_file :image, :default_url => :file_system
validates_attachment_content_type :image, :content_type => [:image, 'audio/mpeg', 'application/mp3', 'application/octet-stream']

上传时出现此错误:

ActiveRecord::UnknownAttributeError in UploadsController#create

unknown attribute: uploaded_data

app/controllers/uploads_controller.rb:24:in `create'

更新:

{"name"=>"TEST", "uploaded_data"=>#<ActionDispatch::Http::UploadedFile:0x00000005518a38 @original_filename="2014-09-26 18.14.22.jpg", @content_type="image/jpeg", @headers="Content-Disposition: form-data; name=\"upload[uploaded_data]\"; filename=\"2014-09-26 18.14.22.jpg\"\r\nContent-Type: image/jpeg\r\n", @tempfile=#<Tempfile:/tmp/RackMultipart20150415-12671-190wpi5>>}

更新:那不是我想要的.数据库中的迁移产生了一些新列，如何返回到以前的版本?有移民命令吗?

Update: thats not that what I wanted. The migration generetad some new columns in database, how can I return to the previus version? is there a demigrate coammand?

推荐答案

要从 Paperclip 恢复迁移，您可以使用:

To revert the migration from Paperclip you can use either:

rake db:migrate:down VERSION=_current_migration_number

或

rake db:rollback

直到您之前的状态.然后你可以像这样创建一个新的迁移:

Until your previous state. Then you can create a new migration like this:

class ChangeUploadToPaperclip < ActiveRecord::Migration
  change do
    rename_column :uploads, :content_type, :upload_content_type 
    rename_column :uploads, :filename, :upload_filename
    rename_column :uploads, :size, :upload_file_size
    add_column :uploads, :upload_updated_at, :datetime
    # Warning: the following will remove your old data, irreversible.
    remove_column :uploads, :width 
    remove_column :uploads, :height 
    remove_column :uploads, :thumbnail 
  end
end

但是您的旧存储和 Paperclips 存储文件的方式之间可能存在潜在错误.

But there could be potential errors between your old storage and Paperclips way of storing files.

在这个答案中，我假设您的模型 has_attached_file :upload.

In this answer I assumed that your model has_attached_file :upload.

如果附加文件有其他名称，请相应地更新每个 upload 和 uploads.

If you have another name for the attached file, update every upload and uploads accordingly.

编辑迁移文件需要有一定的名字:

EditThe migration file needs to have a certain name:

20150417125122_change_upload_to_paperclip.rb

(日期字符串是自动生成的，我从下面的评论中复制了这个.)

(the date-string is auto generated, I copied this from comment below.)

这是因为只有当两者之间有下划线时，Rails 才会查找 ChangeUploadToPaperclip.

This is because Rails will look for ChangeUploadToPaperclip only if there is underscore between.

如果你有 changeuploadtopaperclip.rb，它会寻找 Changeuploadtopaperclip.

If you have changeuploadtopaperclip.rb it would look for Changeuploadtopaperclip.

运行特殊迁移

rake db:migrate:up VERSION=20150417125122

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