ruby-on-rails-3 – 如何制作定制的载波后处理器？

请在GitHub上查看此源文件：
carrierwave/lib/carrierwave/uploader/processing.rb并查看评论.

您将创建自己的CarrierWave上传器子类并将其安装在您的模型中,如下所示：

def MyModel < ActiveRecord::Base

    # this is where the uploaded file will be available in your model,# as a `MyUploader` instance:
    #
    mount_uploader :uploaded_file,MyUploader

    ... 
  end

请注意,它安装在ActiveRecord属性：uploaded_file上.
这意味着当您从模型访问：uploaded_file时,您将获得上载的特定文件的CarrierWave上传器的实例.

您可以在上传器中简单地定义处理,如下所示：

class MyUploader < CarrierWave:Uploader::Base
    process :my_custom_processing => [param1,param2,param3]

    def my_custom_processing(param1,param3)
      ...
      # e.g. you could call a method which is defined elsewhere,# which operates on a file:
      my_nifty_file_processor( self.uploaded_file ) 
      #
      # or you could just do this directly:
      uploaded_data = self.uploaded_file.read
      ...
    end
  end

在my_nifty_file_processor中,您只需对传入的对象调用read即可读取该文件.

CarrierWave允许您在任何上传器实例(=上传文件的任何实例)上调用读取,它将读取该文件.

还有一个提示：

有时您需要访问上传文件的上传器中的ActiveRecord模型.

只需在上传代码中访问它,如下所示：

self.model

这使您可以直接在AR模型中存储有关上载文件的其他信息,例如格式.