A weird mongoid relation

gistfile1.rb

module Abnormal
  module Models
    class Issue
      include Mongoid::Document

      field :exception_class, type: String
      field :message, type: String
      field :uniqueness_hash, type: String
      field :status, type: String, default: OPEN
      field :_id, type: String, default: -> { "#{app_id}#{uniqueness_hash}" }

      has_many :errors, class_name: 'Abnormal::Models::Error', inverse_of: :issue
      belongs_to :app, class_name: 'Abnormal::Models::App', inverse_of: :issues
    end
  end
end

module Abnormal
  module Models
    class Error
      include Mongoid::Document

      field :uniqueness_hash, type: String

      embeds_one :exception, class_name: 'Abnormal::Models::Exception'
      embeds_one :client, class_name: 'Abnormal::Models::Client'
      embeds_one :application_environment, class_name: 'Abnormal::Models::ApplicationEnvironment'
      embeds_one :request, class_name: 'Abnormal::Models::Request'
      field :context, type: Hash
      field :rescue_block, type: Hash

      belongs_to :issue, class_name: 'Abnormal::Models::Issue', inverse_of: :errors
      belongs_to :app, class_name: 'Abnormal::Models::App', inverse_of: :errors

      after_create :find_or_create_issue

      def find_or_create_issue
        _issue = Models::Issue.find_or_create_with_error self

        _issue.errors << self

        _issue
      end
    end
  end
end