Mysql 递归获取多重数组数据

多重数据 $data ，获取顶级下的所有下级id

$data

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" => []
          ]
        ]

] ] ] ]

创建一个方法

     public function getCategoryChildrenIds($data, $lev = 0)
     {
         $arr = [];
         foreach ($data as $key => $value) {
             if ($lev) {
                 $arr[] = $value->id;
             }

             if( isset($value['children'])) {
                 $childLev = $lev + 1;
                 $arr = array_merge($arr, self::getCategoryChildrenIds($value['children'], $childLev));

             }

         }
         return $arr;
     }

获取顶级下所有下级id

array:5 [▼
  0 => 2
  1 => 3
  2 => 5
  3 => 8
  4 => 9
]