Define associations for eager loading when authorizing CanCan resources

cancan_controller.rb

module CanCanController
  extend ActiveSupport::Concern

  included do
    extend(ClassMethods)
    cattr_accessor :cancan_includes
    self.cancan_includes = []
  end

  module ClassMethods
    def cancan_resource_class
      Class.new(super) do
        protected
          def resource_base
            super.includes(@controller.class.cancan_includes)
          end
      end
    end
  end
end