array:3 [▼0 => array:7 [▼"id" => 1"created_at" => "2017-08-05 11:30:15""updated_at" => "2017-08-05 11:30:15""parent_id" => 0"children" => array:1 [▼0 => array:7 [▼"id" => 2"created_at" => "2017-08-05 11:31:11""updated_at" => "2017-08-18 18:57:11""parent_id" => 1"children" => array:1 [▼0 => array:7 [▼"id" => 3"created_at" => "2017-08-05 11:33:34""updated_at" => "2017-08-05 11:33:34""parent_id" => 2"children" => []]]]]]1 => array:7 [▼"id" => 4"created_at" => "2017-08-10 15:36:03""updated_at" => "2017-08-10 15:36:03""parent_id" => 0"children" => array:1 [▼0 => array:7 [▼"id" => 5"created_at" => "2017-08-10 15:36:31""updated_at" => "2017-08-10 15:42:08""parent_id" => 4"children" => []]]]2 => array:7 [▼"id" => 7"created_at" => "2017-08-10 15:47:09""updated_at" => "2017-08-10 15:50:37""parent_id" => 0"children" => array:1 [▼0 => array:7 [▼"id" => 8"created_at" => "2017-08-10 15:47:20""updated_at" => "2017-08-10 15:50:48""parent_id" => 7"children" => array:1 [

　　　　　　 0 => array:7 [▼

            "id" => 9 "created_at" => "2017-08-10 15:49:17" "updated_at" => "2017-08-10 15:51:08" "parent_id" => 8 "children" => [] ]]

] ] ] ]

 1     public function getCategoryChildrenIds($data, $lev = 0)
 2     {
 3         $arr = [];
 4         foreach ($data as $key => $value) {
 5             if ($lev) {
 6                 $arr[] = $value->id;
 7             }
 8
 9             if( isset($value['children'])) {
10                 $childLev = $lev + 1;
11                 $arr = array_merge($arr, self::getCategoryChildrenIds($value['children'], $childLev));
12
13             }
14
15         }
16         return $arr;
17     }

array:5 [▼0 => 21 => 32 => 53 => 84 => 9
]