Rails - Paper_Clip - 支持多文件上传

Question

我在我的Rails 3应用程序上安装了paper_clip,并且可以上传文件 - 哇这很有趣而且简单!

现在的挑战是,允许用户上传多个对象.是否单击选择文件并能够选择多个文件.或者单击更多按钮并获取另一个文件上载按钮.

我无法找到任何教程或宝石来支持这种开箱即用.令人震惊我知道......

任何建议或解决方案.似乎是一个共同的需求？

谢谢

Answer 1

好的,这是一个复杂的,但它是可行的.以下是我如何使用它.

在客户端,我用http://github.com/valums/file-uploader,一个JavaScript库,它允许多个文件上传进度条和拖动和拖放支持.它受到良好支持,高度可配置,基本实现很简单:

在视图中:

<div id='file-uploader'><noscript><p>Please Enable JavaScript to use the file uploader</p></noscript></div>

在js中:

var uploader = new qq.FileUploader({
   element: $('#file-uploader')[0],
   action: 'files/upload',
   onComplete: function(id, fileName, responseJSON){
     // callback
   }
});

当递文件,FileUploader它们张贴到服务器的XHR请求,其中POST主体是原始文件数据,而头和文件名的URL字符串传递(这是上传通过JavaScript asyncronously文件的唯一方法).

这是它变得复杂的地方,因为Paperclip不知道如何处理这些原始请求,你必须捕获它们并将它们转换回标准文件(最好是在它们点击你的Rails应用程序之前),这样Paperclip可以发挥它的魔力.这是通过一些Rack Middleware完成的,它创建了一个新的Tempfile(记住:Heroku是只读的):

# Embarrassing note: This code was adapted from an example I found somewhere online
# if you recoginize any of it please let me know so I pass credit.
module Rack
  class RawFileStubber

    def initialize(app, path=/files\/upload/) # change for your route, careful.
      @app, @path = app, path
    end

    def call(env)
      if env["PATH_INFO"] =~ @path
        convert_and_pass_on(env)
      end
      @app.call(env)
    end

    def convert_and_pass_on(env)
      tempfile = env['rack.input'].to_tempfile      
      fake_file = {
        :filename => env['HTTP_X_FILE_NAME'],
        :type => content_type(env['HTTP_X_FILE_NAME']),
        :tempfile => tempfile
      }
      env['rack.request.form_input'] = env['rack.input']
      env['rack.request.form_hash'] ||= {}
      env['rack.request.query_hash'] ||= {}
      env['rack.request.form_hash']['file'] = fake_file
      env['rack.request.query_hash']['file'] = fake_file
      if query_params = env['HTTP_X_QUERY_PARAMS']
        require 'json'
        params = JSON.parse(query_params)
        env['rack.request.form_hash'].merge!(params)
        env['rack.request.query_hash'].merge!(params)
      end
    end

    def content_type(filename)
      case type = (filename.to_s.match(/\.(\w+)$/)[1] rescue "octet-stream").downcase
      when %r"jp(e|g|eg)"            then "image/jpeg"
      when %r"tiff?"                 then "image/tiff"
      when %r"png", "gif", "bmp"     then "image/#{type}"
      when "txt"                     then "text/plain"
      when %r"html?"                 then "text/html"
      when "js"                      then "application/js"
      when "csv", "xml", "css"       then "text/#{type}"
      else 'application/octet-stream'
      end
    end
  end
end

稍后,在application.rb中:

config.middleware.use 'Rack::RawFileStubber'

然后在控制器中:

  def upload
    @foo = modelWithPaperclip.create({ :img => params[:file] })
  end

这种方法可靠,但在同时上传大量文件时可能会很慢.

免责声明

这是针对具有单个,已知且受信任的后端用户的项目实现的.它几乎肯定会对高流量Heroku应用程序产生一些严重的性能影响,并且我没有为安全性进行过防火测试.那说,它绝对有效.