Mongoid Listable

Mongoid Listable is a library for managing listable relations. It works great for isolated collections or for more complex has_many / embeds_many relationships.

There are two main macros:

• listed for non-relational lists that do not belong to any objects.
  
• lists for has_many / embeds_many relationships.

Basic Usage - Isolated

class Photo
  include Mongoid::Document
  include Mongoid::Listable

  listed
end

The listed macro will assign a position field and a list scope to the Photo class. All Photo instances that are created, destroyed, or have their position field updated will trigger a reording of all sibling instances.

Non-relational lists can have as many listed contexts as needed. You'll need to specify both the scope and the field options in these cases.

class Photo

  include Mongoid::Document
  include Mongoid::Listable

  listed :scope :list, field: :position
  listed :scope :slideshow, field: :slideshow_position

end

Basic Usage - Has Many / Embeds Many

class User
  include Mongoid::Document
  include Mongoid:Listable

  has_many :photos
  # or embeds_many :photos

  lists :photos
  ...
end

class Photo
  include Mongoid::Document

  belongs_to :user
  # or embedded_in :user
  ...
end

In this example photos that are added to or removed from a user's collection, or have their position attribute updated will trigger a reordering of all sibling instances. For example:

# setter
User.first.photos = [ photo_a, photo_c, photo_b ]
User.first.photos.last == photo_b #=> true

# ids setter
User.first.photo_ids = [ '527fe97c67df6f07e1000003', '527fe97c67df6f07e1000004', '527fe97c67df6f07e1000003' ]
User.first.photos[1].id == '527fe97c67df6f07e1000004' #=> true

# push
photo = Photo.create
User.first.photos << photo
User.first.photos.last == photo #=> true

Each photo that belongs to the user will automatically obtain a field called user_position. The field name is derived from the foreign key of the relation, replacing "_id" with "_position". Having a unique position key for each 1-n relationship allows for more complex lists.

The has_many / embeds_many relationship of a user to their photos will automadtically be ordered by user_position unless otherwise specified via the standard order option to the has_many macro.

Advanced Usage - Has Many / Embeds Many

# Handles multiple has_many relations on same model!

class User
  include Mongoid::Document
  include Mongoid:Listable

  has_many :featured_photos, 
  class_name: 'Photo', 
  inverse_of: :featured_by_user, 
  foreign_key: :featured_by_user_id

  has_many :kodak_moments, 
  class_name: 'Photo', 
  inverse_of: :kodaked_by_user, 
  foreign_key: :kodaked_by_user_id

  lists :featured_photos
  lists :kodak_moments
  ...
end

class Photo
  include Mongoid::Document

  belongs_to :featured_by_user, 
  class_name: 'User', 
  inverse_of: featured_photos, 
  foreign_key: :featured_by_user_id

  belongs_to :kodaked_by_user, 
  class_name: 'User', 
  inverse_of: kodak_moments, 
  foreign_key: :kodaked_by_user_id
  ...
end

In this example, there are two has_many relations defined between a user and photos. Each photo belonging to a user will obtain two position fields: featured_by_user_position and kodaked_by_user_position.

Installation

Add this line to your application's Gemfile:

gem 'mongoid_listable'

And then execute:

$ bundle

Or install it yourself as:

$ gem install mongoid_listable

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request