Release: Date: 05-04-2010 Author: Matt Mower <[email protected]> Fork: Jerôme Lipowicz <>

SimplyVersioned is a simple, non-invasive, approach to versioning ActiveRecord models.

SimplyVersioned does not require any structural change to the models to be versioned and requires only one versions table to be created (a migration generator is supplied with the plugin) regardless of the number of models being versioned.

The plugin introduces a 'Version' ActiveRecord model (that reflects changes to model attributes) to which versioned models are polymorphically associated. Version records store the model information as a YAML hash. SimplyVersioned meets a simple need for model versioning. If your needs are more complex maybe try Rick Olsen's acts_as_versioned (

SimplyVersioned is only compatible with Rails 2.1. This pragmatic branch only versions altered records.


  1. Install the lib

1.1 as a plugin:

./script/plugin install git://

1.2 or as a gem:

gem install simply_versioned

# environment.rb
config.gem "simply_versioned"
  1. Generate the migration

./script/generate simply_versioned_migration

Note that the migration defaults to storing the version info in a TEXT field. On MySQL this will default to a limit of 64K. If you are versioning particularly large models you will want to modify the migration to include a :limit => n condition to promote the yaml column to a MEDIUMTEXT or (god forbid) a LONGTEXT.

  1. Create the versions table

rake db:migrate
  1. Annotate the models you want to version specifying how many versions to keep

class Thing < ActiveRecord::Base simply_versioned :keep => 10 end If you do not specify a limit then old versions are never automatically deleted. You can manually delete them like this: thing.versions.purge( 10 ) which would delete all the but the last ten versions. If you want fine-grained control over when versions are created you can use: class Thing < ActiveRecord::Base simply_versioned :automatic => false end and new versions will no longer be created by default. You will then need to use the with_versioning method to create a version. Lastly you can control which columns will be versioned by specifying an exclude parameter. class Thing < ActiveRecord::Base simply_versioned :exclude => :awkward_column end or class Thing < ActiveRecord::Base simply_versioned :exclude => [:first_awkward_column,:second_awkward_column,…] end This may be helpful if you run into conflicts with other plugins which try to manage columns.

  1. Create versions

thing = Thing.create!( :foo => bar ) # creates v1 = baz! # creates v2 If you need to control whether a version is created or not, use #with_versioning. For example: thing.with_versioning( false ) do |t|! end or, using the “magic pen” ( thanks hmj): thing.with_versioning( false, &:save! )

  1. Find versions

thing.versions.each do |version| … end render :partial => 'thing_version', :collection => thing.versions thing.versions.current thing.versions.first thing.versions.get( 3 ) To find a version number: thing.version_number

  1. Revert to a previous version

thing.revert_to_version( 5 ) If a specific reversion needs to avoid overwriting some column values pass an :except option, e.g. thing.revert_to_version( 1, :except => [:name,:age] ) The revert_to_version method also takes an existing Version instance, e.g. version = thing.versions.find( … ) thing.revert_to_version( version )

  1. Traverse versions


  1. Obtain a copy of a previous versioned model

thing.versions.first.model # => Instantiated Thing with versioned values Thanks to:

Josh Susser ( for useful suggestions and feedback Rick Olson ( for all the many plugins whose code i've read Copyright © 2007 Matt Mower <[email protected]> and released under the MIT license Copyright © 2008 Jérôme Lipowicz <> and released under the MIT license