Php output three-stage linkage data json format at one time

has the following data table

then output json data like this at once:

$.rawCitiesData = [
  {
    "name":"",
    "code":"id",
    "sub": [
      {
        "name": "",
        "code": "id",
        "sub":[
            {
              "name":"",
              "code":"110101"
            },
            {
              "name":"",
              "code":"110102"
            },
            {
              "name":"",
              "code":"110105"
            },
            {
              "name":"",
              "code":"110106"
            },
            {
              "name":"",
              "code":"110107"
            },
            {
              "name":"",
              "code":"110108"
            },
            {
              "name":"",
              "code":"110109"
            },
            {
              "name":"",
              "code":"110111"
            },
            {
              "name":"",
              "code":"110112"
            },
            {
              "name":"",
              "code":"110113"
            },
            {
              "name":"",
              "code":"110114"
            },
            {
              "name":"",
              "code":"110115"
            },
            {
              "name":"",
              "code":"110116"
            },
            {
              "name":"",
              "code":"110117"
            },
            {
              "name":"",
              "code":"110228"
            },
            {
              "name":"",
              "code":"110229"
            }
        ]
      }
    ]
  },

< H2 > only the id and name fields in the output data table do not need < / H2 >

data table description
pid=0 means top-level classification
child if equal to 1 means there are subordinate categories

also ask God to teach me how to write this php

<?php // pid // $items = [ [ 'name' => '', 'code' => '1', 'pid' => '0' ], [ 'name' => '', 'code' => '2', 'pid' => '1' ], [ 'name' => '', 'code' => '110101', 'pid' => '2' ], [ 'name' => '', 'code' => '110102', 'pid' => '2' ] ]; $generateTree = function ($items, $parentKey = 'pid') { $tree = $temp = []; foreach ($items as $item) { $temp[$item['code']] = $item; } foreach ($items as $item) { if (isset($temp[$item[$parentKey]])) { $temp[$item[$parentKey]]['sub'][] = &$temp[$item['code']]; } else { $tree[] = &$temp[$item['code']]; } // pid unset($temp[$item['code']][$parentKey]); } return $tree; }; print_r($generateTree($items));