Move ActiveRecord records across tables like it ain't no thang.

sudo gem install mover

Move the last article:

Article.last.move_to(ArticleArchive)

Move today's articles:

Article.move_to(
  ArticleArchive,
  :conditions => [ "created_at > ?", Date.today ]
)

The two tables do not have to be identical. Only shared columns transfer.

If a primary key collision occurs, the destination record is updated.

In this example, we want an "archive" table for articles and comments.

We also want the article's comments to be archived when the article is.

class Article < ActiveRecord::Base
  has_many :comments
  before_move :ArticleArchive do
    comments.each { |c| c.move_to(CommentArchive) }
  end
end

class ArticleArchive < ActiveRecord::Base
  has_many :comments, :class_name => 'CommentArchive', :foreign_key => 'article_id'
  before_move :Article do
    comments.each { |c| c.move_to(Comment) }
  end
end

class Comment < ActiveRecord::Base
  belongs_to :article
end

class CommentArchive < ActiveRecord::Base
  belongs_to :article, :class_name => 'ArticleArchive', :foreign_key => 'article_id'
end

The after_move callback is also available.

If a table contains a moved_at column, it will magically populate with the date and time it was moved.

There are other options, in addition to conditions:

Article.move_to(
  ArticleArchive,
  :copy => true,          # Do not delete Article after move
  :generic => true,       # UPDATE using a JOIN instead of ON DUPLICATE KEY UPDATE (default: false on MySQL engines)
  :magic => 'updated_at', # Custom magic column
  :migrate => true,       # Copies the original value of the magic column
  :quick => true          # You are certain only INSERTs are necessary, no primary key collisions possible
                          # May only be a little faster on MySQL, but dramatically faster on other engines
)

You can access these options from callbacks using move_options.

Before you create a record, you can "reserve a spot" on a table that you will move the record to later.

archive = ArticleArchive.new
archive.id = Article.reserve_id
archive.save