How can I model a polymorphic, custom name relationship using Mongoid

Question

I'm attempting to define a series of model relationships using custom names for a model in some instances, and it's native name in others. Furthermore, the model can be referenced by multiple classes, necessitating a polymorphic relationship.

The following models are simplified (I've removed fields, additional relationships, etc.), but they exemplify the structure I'm attempting to produce while avoid creating inherited models.

class Gallery
  include Mongoid::Document
  embedded_in :galleryable, polymorphic: true
end

class App
  include Mongoid::Document
  embeds_one  :about, class_name: 'Gallery', inverse_of: :galleryable
  embeds_one  :portfolio
end

class Portfolio
  include Mongoid::Document
  embedded_in :app
  embeds_many :galleries, as: :galleryable
end

I understand that the "child" being embedded by a custom relation should also have a class_name definition and an inverse_of:, but how can I define these values without needing to explicitly define the associated class?

Answer 1

You just have to define the association property ":as" :

  class Gallery
    include Mongoid::Document
    embedded_in :galleryable, polymorphic: true
  end

  class App
    include Mongoid::Document
    embeds_one  :about, as: :galleryable
    embeds_one  :portfolio
  end

  class Portfolio
    include Mongoid::Document
    embedded_in :app
    embeds_many :galleries, as: :galleryable
  end

Hope it helps!