php - Create a nested array -

i have table below

• id
  • 1
  • 2
  • 4
• title
  • home page
  • about
  • deneme
• slug
  • home
  • about
  • deneme
• order
  • 1
  • 2
  • 1
• body
  • loremp ipsum
  • dot sit
  • color amet
• parent_id
  • 2
  • 0
  • 0

now, want create nested array table. function below

public function get_nested () {     $pages = $this->db->get('pages')->result_array();     $array = array();     foreach ($pages $page) {         if (! $page['parent_id']) {             $array[$page['id']] = $page;         }         else {             $array[$page['parent_id']]['children'][] = $page;          }     }     return $array; } dump($array); 

when dump $array

dump => array(2) { [2] => array(6) { ["id"] => string(1) "2" ["title"] => string(5) "about" ["slug"] => string(5) "about" ["order"] => string(1) "2" ["body"] => string(241) "lorem ipsum dolor sit amet, consectetur adipisicing elit. ipsam itaque cumque ullam eum atque consectetur voluptates veritatis sapiente voluptatem voluptatibus neque, commodi reprehenderit odit dignissimos omnis, veniam et deserunt incidunt!" ["parent_id"] => string(1) "0" } [4] => array(6) { ["id"] => string(1) "4" ["title"] => string(6) "deneme" ["slug"] => string(6) "deneme" ["order"] => string(1) "1" ["body"] => string(13) "deneme" ["parent_id"] => string(1) "0" } } 

there 2 page list in array there 3 page 1 has parent_id. page has parent_id not showing up. error in else block of get_nested function. error ?

thoroughly @ code , realize when first executes (for parent_id =2),

$array[$page['parent_id']]['children'][] = $page;  

it find $array[2] ($array [2] ['children'] [ ] ) doesn't exists. possible solution sort (orderby) query in ascending order of parent_id.