=Dirty Associations

This plugin adds dirty-attribute-like methods for your model's associations. The usage is very similar to the dirty objects behavior in Rails, except that due to the high database-overhead of the initialization process, you have to explicitly enable this functionality. Once enabled, you get the following methods for specified collection associations (one-to-many, many-to-many):

[collection_changed?] Returns +true+ if the association collection has changed. [collection_added?] Returns +true+ if new records have been added to the association collection. [collection_removed?] Returns +true+ if records have been removed from the association collection. [collection_added] Returns an array of associated objects that have been added to this collection. [collection_removed] Returns an array of associated objects that have been removed from the collection, if they still exist. This will not raise any exceptions if any objects no longer exist, it just won't return them. [collection_were] Returns an array of the association's objects as they were at the start of association tracking. [collection_singular_ids_changed?] Returns +true+ if the association collection has changed. [collection_singular_ids_added?] Returns +true+ if new records have been added to the association collection. [collection_singular_ids_removed?] Returns +true+ if records have been removed from the association collection. [collection_singular_ids_added] Returns an array of associated objects' ids that have been added to the collection. [collection_singular_ids_removed] Returns an array of associated objects' ids that have been removed from the collection. [collection_singular_ids_were] Returns an array of the associated objects' ids as they were at the start of association tracking.

(Note: +collection+ is replaced with name of the tracked association.)

For singular associations (one-to-one), you get these methods:

[association_changed?] Returns +true+ when the association has changed. [association_added?] Returns +true+ if an object was added to a previously empty association. [association_removed?] Returns +true+ if an object was removed from the association, leaving it empty. [association_was] Returns the original object of the association. +nil+ if it no longer exists. [association_id_changed?] Returns +true+ if the association object has changed. [association_id_added?] Returns +true+ if an object was added to a previously empty association. [association_id_removed?] Returns +true+ if an object was removed from the association, leaving it empty. [association_id_was] Returns the original association object's id. [association_id] Returns the current association object's id.

(Note: +association+ is replaced with name of the tracked association.)

And all associations get the following method: [associations_changed?] Returns +true+ if any of the tracked associations have changed.

=Installation

Currently, this only exists as a plugin. You can install it with:

script/plugin install git://github.com/daphonz/dirty_associations.git

=Example

You must specify which associations you would like to make dirty in your model:

class Task < ActiveRecord::Base has_and_belongs_to_many :keywords has_many :blocking_tasks belongs_to :user keep_track_of :keywords, :user end

You specify the scope in which you'll track the changes to the associations by calling enable_dirty_associations on the instantiated model object, which accepts a block. All modifications you make to the object's associations that fall within this block statement are recorded. This record persists throughout the block, but not outside of it:

task = Task.first task.enable_dirty_associations do

task.associations_changed? # false
task.keyword_ids_changed?  # false

task.keywords << Keyword.first
task.keywords << Keyword.last

task.keyword_ids_changed?  # true
task.keyword_ids_removed?  # false
task.keyword_ids_added?    # true
task.keyword_ids_added     # [30,450]
task.keywords_added        # ...collection of keyword objects that were added...
task.keyword_ids_removed   # []

task.create_user(:name => "Joey Joe Joe Jr.")

task.user_changed?         # true
task.user_was              # ...original user object...

end

task.associations_changed? # false

Copyright (c) 2010 Casey Dreier, released under the MIT license.