user.rb

# two-step processing of avatars.
class User < ActiveRecord::Base
  has_attached_file :avatar, 
                    :default_url => "/images/:attachment/:style-missing.gif",
                    :styles => { :medium => "200x200#",
                                 :thumb =>  "55x55#" },
                    :storage => 's3',
                    :s3_credentials => File.join(RAILS_ROOT, 'config', 'app_config.yml'),
                    :bucket => APP_CONFIG[:bucket],
                    :path => APP_CONFIG[:path],
                    :url => APP_CONFIG[:url]
                    
  has_attached_file :local_avatar,
                    :default_url  => "/images/:attachment/:style-missing.gif",
                    :path         => ":rails_root/public/system/:attachment/:id/:style/:filename",
                    :url          => "/system/:attachment/:id/:style/:filename"
                                        
  def process_avatar!
    if local_avatar?
      self.avatar = local_avatar
      self.local_avatar = nil
      save
    end
  end

  def avatar_url(style=nil, only_public=true)
    if !has_public_avatar? && only_public
      "/images/avatars/#{style}-missing.gif"
    else
      (local_avatar? ? local_avatar : avatar).url(style)
    end
  end
end