foodsoft/plugins/documents/app/models/document.rb

class Document < ActiveRecord::Base
  belongs_to :created_by, :class_name => 'User', :foreign_key => 'created_by_user_id'

  validates_presence_of :data

  def filename
    types = MIME::Types[mime]

    if name.include? '.'
      types.each do |type|
        type.extensions.each do |extension|
          return name if name.end_with? ".#{extension}"
        end
      end
    end

    "#{name}.#{types.first.preferred_extension}"
  end

end