Online PHP editor | refs for gRnZQ

<?php $data = [ 0 => [ "category_id" => 20, "category_name" => "Category 1" , "sub_categories" => [ 0 => [ "category_id" => 25, "category_name" => "Category 1.1", "sub_categories" => '' ], 1=> [ "category_id" => 26, "category_name" => "Category 1.2", "sub_categories" => '' ], 2 => [ "category_id" => 27, "category_name" => "Category 1.3", "sub_categories" => [ 0 => [ "category_id" => 31, "category_name" => "Category 2.1", "sub_categories" => '' ], 1=> [ "category_id" => 32, "category_name" => "Category 2.2", "sub_categories" => '' ], ] ], ] ], 1=> [ "category_id" => 21, "category_name" => "Category 2", "sub_categories" => '' ], ]; function getCats($data, array &$ar, $res = ''){ foreach($data as $arr){ $res_new = ''; $res_new .= $arr['category_name'] && $res ? $res.' -> '.$arr['category_name'] : $arr['category_name']; $ar[] = ["category_id"=>$arr['category_id'], "category_name"=>$res_new, ]; // echo $res_new.PHP_EOL; // echo .PHP_EOL; if(is_array($arr['sub_categories'])){ if (count($arr['sub_categories'])>0){ getCats($arr['sub_categories'], $ar, $res_new); } } } } $ares = []; getCats($data,$ares); print_r($ares);