Online PHP editor | refs for fX5Wo

<?php $arr = ['$and'=> ['task.discriminator' => 'filippo', 'status.deleted' => 'asdf']]; $iterator = new RecursiveIteratorIterator(new RecursiveArrayIterator($arr)); $keys = array(); foreach ($iterator as $key => $value) { // Build long key name based on parent keys for ($i = $iterator->getDepth() - 1; $i >= 0; $i--) { $key = $iterator->getSubIterator($i)->key() . '_' . $key; } $keys[] = $key; } var_export($keys);