php递归无限级树形数据，省市区无限树查询案列

摘自：https://gitee.com/mrpzx/tree

数据格式

<?php

return [
    ["id"=>"1","city"=>"中国", "parent_id"=>"0"],
    ["id"=>"2","city"=>"北京", "parent_id"=>"1"],
    ["id"=>"3","city"=>"北京市", "parent_id"=>"2"],
    ["id"=>"4","city"=>"东城区", "parent_id"=>"3"],
    ["id"=>"5","city"=>"西城区", "parent_id"=>"3"],
    ["id"=>"6","city"=>"丰台区", "parent_id"=>"3"],
    ["id"=>"7","city"=>"海淀区", "parent_id"=>"3"],
    ["id"=>"8","city"=>"房山区", "parent_id"=>"3"],
    ["id"=>"9","city"=>"通州区", "parent_id"=>"3"],
    ["id"=>"10","city"=>"昌平区", "parent_id"=>"3"],
    ["id"=>"11","city"=>"上海", "parent_id"=>"1"],
    ["id"=>"12","city"=>"上海市", "parent_id"=>"11"],
    ["id"=>"13","city"=>"黄浦区", "parent_id"=>"11"],
    ["id"=>"14","city"=>"长宁区", "parent_id"=>"11"],
    ["id"=>"15","city"=>"卢湾区", "parent_id"=>"11"],
    ["id"=>"16","city"=>"徐汇区", "parent_id"=>"11"],
    ["id"=>"17","city"=>"普陀区", "parent_id"=>"11"],
    ["id"=>"18","city"=>"闸北区", "parent_id"=>"11"],
    ["id"=>"19","city"=>"虹口区", "parent_id"=>"11"],
];

工具类

<?php
declare(strict_types=1);

/**
 * 自定义省市区无限树
 * Class CityTree
 * @package app\utils
 */
class CityTree
{
    /**
     * 主键名称，根据实际来写
     * @var string
     */
    private static $primary = 'id';

    /**
     * 父键名称，根据实际来写
     * @var string
     */
    private static $parentId = 'parent_id';

    /**
     * 子节点名称
     * @var string
     */
    private static $child    = 'child';

    /**
     * 修改主键名称、父键名称、子节点名称
     * @param string $primary
     * @param string $parentId
     * @param string $child
     */
    public static function setConfig($primary = '', $parentId = '', $child = ''){
        if(!empty($primary))  self::$primary  = $primary;
        if(!empty($parentId)) self::$parentId = $parentId;
        if(!empty($child))    self::$child    = $child;
    }

    /**
     * 生成Tree
     * @param array $data
     * @param number $index
     * @return array
     */
    public static function  makeTree(&$data, $index = 0)
    {
        $childs = self::findChild($data, $index);
        if(empty($childs))
        {
            return $childs;
        }
        foreach($childs as $k => &$v)
        {
            if(empty($data)) break;
            $child = self::makeTree($data, $v[self::$primary]);
            if(!empty($child))
            {
                $v[self::$child] = $child;
            }
        }
        unset($v);
        return $childs;
    }

    /**
     * 查找子类
     * @param array $data
     * @param number $index
     * @return array
     */
    public static function findChild(&$data, $index)
    {
        $childs = [];
        foreach ($data as $k => $v){
            if($v[self::$parentId] == $index){
                $childs[]  = $v;
                unset($v);
            }
        }
        return $childs;
    }

}