merge all sub level arrays into one level

MenuController.php

<?php
class MenuController extends Controller
{

    public function parseJsonArray($jsonArray, $parentID = 0) {
        $return = array();
        foreach ($jsonArray as $subArray) {
            $returnSubSubArray = array();
            if (isset($subArray->children)) {
                $returnSubSubArray = $this->parseJsonArray($subArray->children, $subArray->id);
            }
            $return[] = array('id' => $subArray->id, 'parentID' => $parentID);
            $return = array_merge($return, $returnSubSubArray);
        }
        return $return;
    }
    
    public function index()
    {
        $json = "[{\"id\":8,\"name\":\"name\",\"children\":[{\"id\":7,\"name\":\"name\",\"children\":[{\"id\":6,\"name\":\"name6\"},{\"id\":5,\"name\":\"name5\"}]}]},{\"id\":4,\"name\":\"name4\"},{\"id\":3,\"name\":\"name3\"},{\"id\":2,\"name\":\"name\"},{\"id\":1,\"name\":\"name\"}]";
        $json = json_decode($json);
        $readbleArray = $this->parseJsonArray($json);
        print_r($readbleArray);

    }