php 无限级分类，获得树形数组

category.php

<?php
// ...

public static function getCategory($pid = 0){
    $tmp = Category::where('pid', $pid)->get()->toArray();
    $category = [];

    if (count($tmp) != 0){
        foreach ($tmp as $key => $value){
            // 通过递归处理获得子类
            $value['sub'] = self::getCategory($value['id']);
            $category[] = $value;
        }
    }
    return $category;
}
// ...