autocde2.0/app/Http/Resources/API/DepartmentResource.php

<?php
/**
 * Created by IntelliJ IDEA.
 * User: kelyliang
 * Date: 2024/2/29
 * Time: 上午 11:46
 */

namespace App\Http\Resources\API;

use Illuminate\Http\Request;
use Illuminate\Http\Resources\Json\JsonResource;

class DepartmentResource extends JsonResource
{
    public function toArray(Request $request): array
    {
        return[
          'id' => $this->id,
          'name' => $this->name,
          'parent_id'  => $this->parent_id,
          'manager_id' => $this->manager_id,
          'children' => $this->when($this->children->isNotEmpty(),function (){
                return $this->children->map(function ($child){
                    return new DepartmentResource($child);
                })->all();
            }),
          'created_at' => (string)$this->created_at,
        ];
    }
}