A Rails plugin that provides list abilities to an ActiveRecord model

View the Project on GitHub swanandp/acts_as_list



This acts_as extension provides the capabilities for sorting and reordering a number of objects in a list. The class that has this specified needs to have a position column defined as an integer on the mapped database table.


In your Gemfile:

gem 'acts_as_list'

Or, from the command line:

gem install acts_as_list


At first, you need to add a position column to desired table:

rails g migration AddPositionToTodoItem position:integer
rake db:migrate

After that you can use acts_as_list method in the model:

class TodoList < ActiveRecord::Base
  has_many :todo_items, -> { order("position ASC") }

class TodoItem < ActiveRecord::Base
  belongs_to :todo_list
  acts_as_list scope: :todo_list


Instance Methods Added To ActiveRecord Models

You'll have a number of methods added to each instance of the ActiveRecord model that to which acts_as_list is added.

In acts_as_list, "higher" means further up the list (a lower position), and "lower" means further down the list (a higher position). That can be confusing, so it might make sense to add tests that validate that you're using the right method given your context.

Methods That Change Position and Reorder List

Methods That Change Position Without Reordering List

Methods That Return Attributes of the Item's List Position


If the position column has a default value, then there is a slight change in behavior, i.e if you have 4 items in the list, and you insert 1, with a default position 0, it would be pushed to the bottom of the list. Please look at the tests for this and some recent pull requests for discussions related to this.

All position queries (select, update, etc.) inside gem methods are executed without the default scope (i.e. Model.unscoped), this will prevent nasty issues when the default scope is different from acts_as_list scope.

The position column is set after validations are called, so you should not put a presence validation on the position column.

If you need a scope by a non-association field you should pass an array, containing field name, to a scope:

class TodoItem < ActiveRecord::Base
  # `kind` is a plain text field (e.g. 'work', 'shopping', 'meeting'), not an association
  acts_as_list scope: [:kind]


All versions 0.1.5 onwards require Rails 3.0.x and higher.

Build Status

Build Status


  1. Sort based feature
  2. Rails 4 compatibility and bye bye Rails 2! Older versions would of course continue to work with Rails 2, but there won't be any support on those.

Contributing to acts_as_list


Copyright (c) 2007 David Heinemeier Hansson, released under the MIT license