Acts As Favable

acts_as_favable is a small Active Record extension for adding polymorphic favorites to multiple models.

The gem keeps its original API while modernizing the integration for current Rails applications: lazy Active Record loading, Rails-aware polymorphic type handling, a version-aware generator, automated tests, and a CI compatibility matrix.

Compatibility

The minimum supported Rails version is Rails 7.2.

The project is tested against:

• Ruby 3.1 with Rails 7.2
• Ruby 3.2 with Rails 8.0
• Ruby 3.2, 3.3, 3.4, and 4.0 with Rails 8.1

Rails 8.1 is the primary current target, while Rails 7.2 is an intentionally supported compatibility floor rather than a best-effort legacy lane. Changes to the gem should continue to preserve Rails 7.2 compatibility unless the minimum supported version is explicitly raised in a future release.

Applications should still follow the upstream Rails maintenance policy when choosing a production Rails version.

Installation

Add the gem to your application's Gemfile:

gem "acts_as_favable"

Then install dependencies and generate the model and migration:

bundle install
bin/rails generate favorite
bin/rails db:migrate

The generator uses the migration version of the Rails version running your application. It does not hard-code a specific Rails migration version.

Usage

Make any Active Record model favable:

class Article < ApplicationRecord
  acts_as_favable
end

Create favorites through the association:

article = Article.find(1)
article.favorites.create!(note: "Read this again")

Optional user association

The generated Favorite model intentionally defines user as optional:

class Favorite < ApplicationRecord
  include ActsAsFavable::Favorite

  belongs_to :favable, polymorphic: true
  belongs_to :user, optional: true
end

This is the default gem policy. A favorite can exist without a user:

article.favorites.create!(note: "Read this again")

Applications that associate favorites with users can still pass one normally:

article.favorites.create!(
  note: "Read this again",
  user: current_user
)

If every favorite in a particular application must belong to a user, that application can tighten the generated model to belongs_to :user and make user_id non-null in its migration before running it. The gem itself will continue to generate an optional user association by default.

Querying favorites

The generated Favorite model includes two explicit ordering scopes:

article.favorites.recent
article.favorites.in_order

The original finder API is also supported:

Article.find_favorites_for(article)
Article.find_favorites_by_user(user)

Favorite.find_favorites_by_user(user)
Favorite.find_favorites_for_favable(Article.polymorphic_name, article.id)
Favorite.find_favable(favorite.favable_type, favorite.favable_id)

acts_as_favable uses Active Record's polymorphic naming APIs, so finder behavior follows Rails' STI and namespacing rules instead of reimplementing them.

Association options

Options passed to acts_as_favable are forwarded to the generated has_many :favorites association. The default is dependent: :destroy.

class AuditRecord < ApplicationRecord
  acts_as_favable dependent: :delete_all
end

Generated files

bin/rails generate favorite creates:

app/models/favorite.rb
db/migrate/<timestamp>_create_favorites.rb

The migration creates indexed favable_type, favable_id, and user_id columns. The polymorphic target is required; user_id is nullable by design.

Upgrading from older versions

Older versions of this project originated as a Rails plugin. Modern Rails applications do not use the historical init.rb or install.rb plugin entry points.

If you are upgrading an existing application, review your existing favorites table and model before running the generator. The generator is intended for new installations; it should not replace an existing migration or model without review.

The generated model no longer adds a default_scope. Use recent or in_order explicitly where ordering matters. Existing application models are not changed automatically.

Development

Install dependencies and run the test suite:

bundle install
bundle exec rake test

Run against a specific supported Rails series:

RAILS_VERSION=7.2 bundle exec rake test
RAILS_VERSION=8.0 bundle exec rake test
RAILS_VERSION=8.1 bundle exec rake test

Rails 7.2 is the compatibility floor and must remain represented in CI while it is a supported gem target.

Build the gem locally:

bundle exec rake build

See CONTRIBUTING.md for contribution guidelines and CHANGELOG.md for notable changes.

License

MIT. See MIT-LICENSE.

Credits

The original implementation was influenced by the early Rails acts_as_* plugin ecosystem, including acts_as_taggable and acts_as_commentable-style projects.