Recursive funciton in Codeigniter

[eluser]foysal[/eluser]
I searched a lot in Google "adjacency list using codeigniter" but could not get any solution .

I am trying now with following function of model.

Code:

public function user_list($user_id)
{
  $query_parent_user = $this->db->get_where('users',array('user_parent_user_id'=>$user_id,'user_type'=>3,'user_status'=>1));
  $results_parent_user  = $query_parent_user->result();
  $user_array[] = $results_parent_user[0]->user_id;
  if(empty($results_parent_user))
  {
   return $user_array;
  }
  else
  {
   foreach($results_parent_user as $result_parent_user)
   {
    $query_child_user = $this->db->get_where('users',array('user_parent_user_id'=>$result->user_parent_user_id,'user_type'=>3,'user_status'=>1));
    $results_child_user  = $query_child_user->result();
    $user_array[] = $results_child_user[0]->user_id;
    $this->user_list($results_child_user[0]->user_parent_user_id);
   }
  }
  
}