There is another gem called secretary, which hasn't been updated since 2008 and is obsolete. This gem is called secretary-rails since secretary is already taken on RubyGems. However, the module name is the same, so using them together would be difficult.

Light-weight model versioning for ActiveRecord 3.2+.

Whenever you save your model, a new version is saved. The changes are serialized and stored in the database, along with a version description, foreign keys to the object, and a foreign key to the user who saved the object.

• It tracks associations.
• It provides diffs (using the diffy gem).
• It only stores the changes, not the whole object.
• It is simple.

• Rails 4+ (For 3.2 support, use secretary-rails ~> 1.0)
• Ruby 2.0+
• SQLite
• MySQL
• PostgreSQL

• activerecord >= 3.2.0
• railties >= 3.2.0
• diffy ~> 3.0.1

Add to your gemfile:

gem 'secretary-rails'

Run the install command, which will create a migration to add the versions table, and then run the migration:

bundle exec rails generate secretary:install
bundle exec rake db:migrate

Add the has_secretary macro to your model:

class Article < ActiveRecord::Base
  has_secretary
end

Congratulations, now your records are being versioned.

This gem is built with the end-user in mind, so it doesn't track hidden associations (i.e. join models). However, you can tell it to track associated objects WITHIN their parent object's version by using the tracks_association macro. For example:

class Author < ActiveRecord::Base
  has_many :article_authors
  has_many :articles, through: :article_authors
end

class ArticleAuthor < ActiveRecord::Base
  belongs_to :article
  belongs_to :author
end

class Article < ActiveRecord::Base
  has_secretary

  has_many :article_authors
  has_many :authors, through: :article_authors
  tracks_association :authors
end

Now, when you save an Article, a new version won't be created for the new ArticleAuthor object(s). Instead, an array will be added to the Article's changes, which will include the information about the author(s).

You can also pass in multiple association names into tracks_association.

This also works on all other association types in the same way:

• has_many
• has_many :through
• has_and_belongs_to_many
• has_one
• belongs_to

Secretary provides Rails-style dirty attributes for associations. Given an association has_many :pets, the methods available are:

• pets_changed?
• pets_were

Secretary also merges in the association changes into the standard Rails changes hash:

person.pets.to_a # => []

person.pets << Pet.new(name: "Spot")

person.pets_changed? # => true
person.changed?      # => true
person.pets_were     # => []
person.changes       # => { "pets" => [[], [{ "name" => "Spot" }]]}

A version has an association to a user object, which tells you who created that version. The logged user is an attribute on the object being changed, so you can add it in via the controller:

class ArticlesController < ApplicationControler
  before_filter :get_object, only: [:show, :edit, :update, :destroy]
  before_filter :inject_logged_user, only: [:update]

  def create
    @article = Article.new(article_params)
    inject_logged_user
    # ...
  end

  # ...

  private

  def get_object
    @article = Article.find(params[:id])
  end

  def inject_logged_user
    @article.logged_user_id = @current_user.id
  end
end

Protip: Using outpost-secretary? This is taken care of for you. Just be sure to add the logged_user_id to your Strong Parameters.

The Secretary::Version model allows you to see unix-style diffs of the changes, using the diffy gem. The diffs are represented as a hash, where the key is the name of the attribute, and the value is the Diffy::Diff object.

article = Article.new(headline: "Old Headline", body: "Lorem ipsum...")
article.save

article.update_attributes(headline: "Updated Headline", body: "Updated Body")

last_version = article.versions.last
puts last_version.attribute_diffs

{"headline"=>
  -Old Headline
\ No newline at end of file
+Updated Headline
\ No newline at end of file
,
 "body"=>
  -Lorem ipsum...
\ No newline at end of file
+Updated Body
\ No newline at end of file
}

This is just the simple text representation of the Diffy::Diff objects. Diffy also provides several other output formats. See diffy's README for more options.

The install task will create an initializer for you with the following options:

• user_class - The class for your user model.
• ignored_attributes - The attributes which should always be ignored when generating a version, for every model, as an array of Strings.

Sometimes you have an attribute on your model that either isn't public (not in the form), or you just don't want to version. You can tell Secretary to ignore these attributes globally by setting Secretary.config.ignore_attributes. You can also ignore attributes on a per-model basis by using one of two options:

NOTE The attributes must be specified as Strings.

class Article < ActiveRecord::Base
  # Inclusion
  has_secretary on: ["headline", "body"]
end

class Article < ActiveRecord::Base
# Exclusion
  has_secretary except: ["published_at", "is_editable"]
end

By default, the versioned attributes are: the model's column names, minus the globally configured ignored_attributes, minus any excluded attributes you have set.

Using tracks_association adds those associations to the versioned_attributes array:

class Article < ActiveRecord::Base
  has_secretary on: ["headline"]

  has_many :images
  tracks_association :images
end

Article.versioned_attributes # => ["headline", "images"]

There is one aspect that may seem a bit confusing. The behavior of record.changes, and other Dirty attribute methods from ActiveModel, is preserved, so any attribute you change will be added to the record's changes. However, this does not necessarily mean that a version will be created, because you may have changed an attribute that isn't versioned. For example:

class Article < ActiveRecord::Base
  has_secretary on: ["headline", "body"]
end

article = Article.find(1)
article.changed? #=> false

article.slug = "new-slug-for-article" # "slug" is not versioned
article.changed? #=> true
article.changed #=> ["slug"]

article.versioned_changes #=> {}
article.save! # A new version isn't created!

This also goes for associations: if you change an association on a parent object, but in an "insignificant" way (i.e., no versioned attributes are changed), then that association won't be considered "changed" when it comes time to build the version.

Fork it and send a pull request!

• See Issues.
• Add support for other ORM's besides ActiveRecord.
• Associations are only tracked one-level deep, It would be nice to also track the changes of the association (i.e. recognize when an associated object was changed and show its changed, instead of just showing a whole new object).

Running the full suite requires that you have SQLite, MySQL, and Postgres servers all installed and running. Once you have them setup, setup the databases by running bundle exec rake test:setup. This will create the databases you need. You should only need to run this once.

If you get a message like FATAL: database "combustion_test" does not exist when running rake test:setup, it's okay (you can ignore it). The database gets created anyways.

Secretary uses the appraisals gem to run its tests across different versions of Rails.

Run rake -T to see all of the options for running the tests.

To run the full test suite:

$ bundle exec rake test