Inserting data to several tables using Faker Populator, a custom formatter, and Propel

gistfile1.aw

<?php
$faker = \Faker\Factory::create();
$populator = new \Faker\ORM\Propel\Populator($faker);
$populator->addEntity('Author', 10000);
$populator->addEntity('Book',   100000, $customColumnFormatters = array(
  'ISBN' => function () use ($generator) { return $generator->randomNumber(13); },
));
$populator->addEntity('Review', 1000000);
$insertedPKs = $populator->execute();