migrate_products_to_paperclip.rb

class MigrateProductsToPaperclip < ActiveRecord::Migration
  def self.up
    
    # Rename the old "image" column to "old_file_name", since Product.image will now try to do Paperclip stuff
    rename_column :products, :image, :old_file_name

    # Rename asset directories to pluralize
    File.rename("public/system/product","public/system/products")
    File.rename("public/system/products/image","public/system/products/images")

    Product.all.each do |p|
      unless p.old_file_name.blank?

        # If an image was set by file_column, copy the relevant parameters to the new Paperclip columns
        p.update_attributes(
        :image_file_name => p.old_file_name,
        :image_content_type => 'image/jpeg',
        :image_updated_at => Time.now.utc,
        :image_file_size => File.stat("public/system/products/images/#{p.id}/#{p.old_file_name}").size)

        # Now rename the image file to add the original_ prefix
        File.rename("public/system/products/images/#{p.id}/#{p.old_file_name}","public/system/products/images/#{p.id}/original_#{p.old_file_name}")
      end

    end

    # And finally remove the old_file_name column, which we don't need any more
    remove_column :products, :old_file_name
  end

  def self.down

    # laziness, impatience, hubris
    raise IrreversibleMigration
  end
end