Module Include

The module_include plugin allows you to extend Shrine's core classes for the given uploader with modules/methods.

plugin :module_include

To add a module to a core class, call the appropriate method:

attachment_module CustomAttachmentMethods
attacher_module CustomAttacherMethods
file_module CustomFileMethods

Alternatively you can pass in a block (which internally creates a module):

attachment_module do
  def included(model)
    super

    name = attachment_name

    define_method :"#{name}_size" do |version|
      attachment = send(name)
      if attachment.is_a?(Hash)
        attachment[version].size
      elsif attachment
        attachment.size
      end
    end
  end
end

The above defines an additional #<attachment>_size method on the attachment module, which is what is included in your model.