mongoid-history

Mongoid-history tracks historical changes for any document, including embedded ones. It achieves this by storing all history tracks in a single collection that you define. Embedded documents are referenced by storing an association path, which is an array of document_name and document_id fields starting from the top most parent document and down to the embedded document that should track history.

This gem also implements multi-user undo, which allows users to undo any history change in any order. Undoing a document also creates a new history track. This is great for auditing and preventing vandalism, but is probably not suitable for use cases such as a wiki.

Stable Release

You're reading the documentation the 0.3.x release that supports Mongoid 3.x. For 2.x compatible mongoid-history, please use a 0.2.x version from the 2.x-stable branch.

Install

This gem supports Mongoid 3.x on Ruby 1.9.3 only. Add it to your Gemfile or run gem install mongoid-history.

gem 'mongoid-history'

Usage

Create a history tracker

Create a new class to track histories. All histories are stored in this tracker. The name of the class can be anything you like. The only requirement is that it includes Mongoid::History::Tracker

# app/models/history_tracker.rb
class HistoryTracker
  include Mongoid::History::Tracker
end

Set tracker class name

Manually set the tracker class name to make sure your tracker can be found and loaded properly. You can skip this step if you manually require your tracker before using any trackables.

The following example sets the tracker class name using a Rails initializer.

# config/initializers/mongoid-history.rb
# initializer for mongoid-history
# assuming HistoryTracker is your tracker class
Mongoid::History.tracker_class_name = :history_tracker

Set #current_user method name

You can set the name of the method that returns currently logged in user if you don't want to set modifier explicitly on every update.

The following example sets the current_user_method using a Rails initializer

# config/initializers/mongoid-history.rb
# initializer for mongoid-history
# assuming you're using devise/authlogic
Mongoid::History.current_user_method = :current_user

When current_user_method is set, mongoid-history will invoke this method on each update and set its result as the instance modifier.

# assume that current_user return #<User _id: 1>
post = Post.first
post.update_attributes(:title => 'New title')

post.history_tracks.last.modifier #=> #<User _id: 1>

Create trackable classes and objects

class Post
  include Mongoid::Document
  include Mongoid::Timestamps

  # history tracking all Post documents
  # note: tracking will not work until #track_history is invoked
  include Mongoid::History::Trackable

  field           :title
  field           :body
  field           :rating
  embeds_many     :comments

  # telling Mongoid::History how you want to track changes
  track_history   :on => [:title, :body],       # track title and body fields only, default is :all
                  :modifier_field => :modifier, # adds "belongs_to :modifier" to track who made the change, default is :modifier
                  :modifier_field_inverse_of => :nil, # adds an ":inverse_of" option to the "belongs_to :modifier" relation, default is not set
                  :version_field => :version,   # adds "field :version, :type => Integer" to track current version, default is :version
                  :track_create   =>  false,    # track document creation, default is false
                  :track_update   =>  true,     # track document updates, default is true
                  :track_destroy  =>  false,    # track document destruction, default is false
end

class Comment
  include Mongoid::Document
  include Mongoid::Timestamps

  # declare that we want to track comments
  include Mongoid::History::Trackable

  field             :title
  field             :body
  embedded_in       :post, :inverse_of => :comments

  # track title and body for all comments, scope it to post (the parent)
  # also track creation and destruction
  track_history     :on => [:title, :body], :scope => :post, :track_create => true, :track_destroy => true
end

# the modifier class
class User
  include Mongoid::Document
  include Mongoid::Timestamps

  field             :name
end

user = User.create(:name => "Aaron")
post = Post.create(:title => "Test", :body => "Post", :modifier => user)
comment = post.comments.create(:title => "test", :body => "comment", :modifier => user)
comment.history_tracks.count # should be 1

comment.update_attributes(:title => "Test 2")
comment.history_tracks.count # should be 2

track = comment.history_tracks.last

track.undo! user # comment title should be "Test"

track.redo! user # comment title should be "Test 2"

# undo last change
comment.undo! user

# undo versions 1 - 4
comment.undo! user, :from => 4, :to => 1

# undo last 3 versions
comment.undo! user, :last => 3

# redo versions 1 - 4
comment.redo! user, :from => 1, :to => 4

# redo last 3 versions
comment.redo! user, :last => 3

# delete post
post.destroy

# undelete post
post.undo! user

# disable tracking for comments within a block
Comment.disable_tracking do
  comment.update_attributes(:title => "Test 3")
end

Retrieving the list of tracked fields

class Book
  ...
  field             :title
  field             :author
  field             :price
  track_history     :on => [:title, :price]
end

Book.tracked_fields           #=> ["title", "price"]
Book.tracked_field?(:title)   #=> true
Book.tracked_field?(:author)  #=> false

Displaying history trackers as an audit trail

In your Controller:

# Fetch history trackers
@trackers = HistoryTracker.limit(25)

# get change set for the first tracker
@changes = @trackers.first.tracked_changes
  #=> {field: {to: val1, from: val2}}

# get edit set for the first tracker
@edits = @trackers.first.tracked_changes
  #=> { add: {field: val},
  #     remove: {field: val},
  #     modify: { to: val1, from: val2 },
  #     array: { add: [val2], remove: [val1] } }

In your View, you might do something like (example in HAML format):

%ul.changes
  - (@edits[:add]||[]).each do |k,v|
    %li.remove Added field #{k} value #{v}

  - (@edits[:modify]||[]).each do |k,v|
    %li.modify Changed field #{k} from #{v[:from]} to #{v[:to]}

  - (@edits[:array]||[]).each do |k,v|
    %li.modify
      - if v[:remove].nil?
        Changed field #{k} by adding #{v[:add]}
      - elsif v[:add].nil?
        Changed field #{k} by removing #{v[:remove]}
      - else
        Changed field #{k} by adding #{v[:add]} and removing #{v[:remove]}

  - (@edits[:remove]||[]).each do |k,v|
    %li.remove Removed field #{k} (was previously #{v})

For more examples, check out spec/integration/integration_spec.rb.

Contributing to mongoid-history

• Check out the latest code to make sure the feature hasn't been implemented or the bug hasn't been fixed yet.
• Check out the issue tracker to make sure someone already hasn't requested it and/or contributed it.
• Fork the project.
• Create a feature/bugfix branch.
• Commit and push until you are happy with your changes.
• Make sure to add tests.
• Update the CHANGELOG for the next release.
• Try not to mess with the Rakefile or version.
• Make a pull request.

Copyright

Copyright (c) 2011-2012 Aaron Qian. MIT License.

See LICENSE.txt for further details.