Async mailing with Devise, DelayedJob and devise-async

devise_async_delayed_job_i18n.rb

require 'devise/async'
require 'devise/async/backend/base'
require 'devise/async/backend/delayed_job'

if defined?(Devise::Async::Backend::Base) && defined?(Devise::Async::Backend::DelayedJob)
  module Devise
    module Async
      module Backend
        class Base
          def perform_with_locale(method, resource_class, resource_id, opts, locale)
            resource = resource_class.constantize.to_adapter.get!(resource_id)
            opts.symbolize_keys!
            I18n.with_locale(locale) do
              mailer_class.send(method, resource, opts).deliver
            end
          end
        end
        class DelayedJob < Base
          def self.enqueue(*args)
            new.delay(:queue => Devise::Async.queue).perform_with_locale(*args + [I18n.locale])
          end
        end
      end
    end
  end
else
  raise "Cannot initialize Devise Async backend properly! Critical!"
end