Paperclip migration rename, add and remove helpers

gistfile1.rb

class UserRenameAvatarToProfileRemoveAAddB < ActiveRecord::Migration
  # you may want to change these
  AttachmentColumns = [["file_name", :string], ["content_type", :string], ["file_size", :integer]]
  # make sure this matches your setup, also have a look in the rename and remove methods
  AttachmentPath = Rails.root.join("public", "system")

  def self.rename_attachment(table, old, new)
    AttachmentColumns.each do |suffix, type|
      rename_column table, "#{old}_#{suffix}", "#{new}_#{suffix}"
    end
    begin
      File.rename AttachmentPath.join(table.to_s, old.to_s.pluralize), AttachmentPath.join(table.to_s, new.to_s.pluralize)
    rescue SystemCallError
    end
  end

  def self.remove_attachment(table, name)
    AttachmentColumns.each do |suffix, type|
      remove_column table, "#{name}_#{suffix}"
    end
    FileUtils.rm_r AttachmentPath.join(table.to_s, name.to_s.pluralize), :force => true, :secure => true
  end
  
  def self.add_attachment(table, name)
    AttachmentColumns.each do |suffix, type|
      add_column table, "#{name}_#{suffix}", type
    end
  end
  
  # example up/down methods
  def self.up
    rename_attachment :users, :avatar_image, :profile_image
    remove_attachment :users, :a_image
    add_attachment :users, :b_image
  end

  def self.down
    rename_attachment :users, :profile_image, :avatar_image
    add_attachment :users, :a_image
    remove_attachment :users, :b_image
  end
end