Polymorphic association in a grape entity

polymorphic_ass_grape_entity

require_relative 'customer.rb'
require_relative 'contact.rb'
require_relative 'agent.rb'

module Api
  module V1
    module Entities
      
      class Ticket < Grape::Entity
        expose :id
        expose :subject
        expose :description
        expose :customer, using: Api::V1::Entities::Customer
        expose :contact, using: Api::V1::Entities::Contact
        expose :created_by do |ticket, options|
          if ticket.created_by.class.to_s == 'Contact'
            { "contact" => Api::V1::Entities::Contact.represent(ticket.created_by) }
          else
            { "agent" => Api::V1::Entities::Agent.represent(ticket.created_by) }
          end
        end
        expose :created_at
        expose :updated_at
      end

    end
  end
end