I reopend this https://github.com/mongoid/mongoid/issues/1207 because i think there is need to rediscuss this. Is easer to to migrate from AR to Mongoid if there some equals, so this is my reason to talk about about this.

ActiveRecord have association scoping http://guides.rubyonrails.org/association_basics.html#controlling-association-scope and is very smart.

when you have something like this:

module Access
  class Website
    has_many :users, inverse_of: :website
    has_many :posts, inverse_of: :account
  end

  class User
    belongs_to :website, inverse_of: :users
  end
end

class Post
  belongs_to :website, inverse_of: posts, class_name: 'Access::Website'
end

And this works because module scoping traverse from down to up. So association within module it search for another associations. Finds what's exists and go up. Another association are found on top of scoping (i thinks it is App models directory).

No need to defined class_names is more clear (for me definitely), because is able to define namespacing blocks of app, and if you communicate within module you know that are associations without class names.

This also works with multiple nested namespace

module Website
  module Access
    class Account
      has_many :users, inverse_of: :account
    end
  end
    
  class User
    belongs_to :account, inverse_of: :users, class_name: 'Access::Account'
  end
end

R.