Idea for a nested resource controller helper

nested_resource.rb

# Provides a helper method for controllers who need to query a nested resource.
# Implements per-request in-memory caching for nested resources as well as
# support for controllers that are also accessed without being nested.
module NestedResource
  DEFAULT_OPTIONS = {
    optional: false,
    class_name: nil,
    param: nil
  }

  # Defines a method named the same as the passed `name` on the calling class
  # which returns the specified resource.
  #
  # Options (with defaults):
  # * `optional`: *false* Set to true if ActiveSupport::RecordNotFound should be
  #   raised if a record can't be found.
  # * `class_name`: *nil* Set to the name of a class you would like to search
  #   on. Defaults to a classified `name`.
  # * `param`: *nil* Set to the key to check in  `params` for the nested
  #   resource's `#id`. Defaults to the passed `name` with "_id" appended.
  #
  # Example:
  #
  #   class OrdersController < ApplicationController
  #     extend NestedResource
  #
  #     nested_resouce :user, optional: true
  #
  #     def index
  #       @orders = user ? user.orders : []
  #     end
  #   end
  def nested_resource(name, options = {})
    options = options.reverse_merge(DEFAULT_OPTIONS)

    # String#classify will be a noop on options[:class_name]
    klass = (options[:class_name] || name.to_s).classify.constantize
    ivar = "@#{name}"
    param = options[:param] || "#{name}_id"

    helper_method name

    define_method name do
      Rails.logger.info "lol"
      if instance_variable_defined?(ivar)
        instance_variable_get(ivar)
      else
        find_method = options[:optional] && !params[param] ? :find_by_id : :find
        order = klass.send(find_method, params[param])
        instance_variable_set(ivar, order)
      end
    end
  end
end