baoshi-was/app/Services/CityService.php

<?php

namespace App\Services;

use App\City;

Class CityService
{
    /*
     * array | string $column
     * 默认一些select字段,可传递string 或 array来指定select字段
     */
    public function getSelection($column = ['id','name']){
        if (!is_array($column)) {
            $column = [$column];
        }
        return City::query()->select($column)->get();
    }

    public function find($id){
        return City::query()->find($id);
    }

}