- json_decode: documentation ( source)
<?php
$data = "{\"data\":[{\"id\":1,\"parent\":1,\"order\":1,\"step_id\":1},{\"id\":2,\"parent\":1,\"order\":2,\"step_id\":2},{\"id\":3,\"parent\":1,\"order\":3,\"step_id\":3},{\"id\":4,\"parent\":1,\"order\":4,\"step_id\":4},{\"id\":5,\"parent\":1,\"order\":5,\"step_id\":5}]}";
echo json_decode($data);