source: database/seeders/FoldersTableSeeder.php

<?php

namespace Database\Seeders;

use App\Models\Department;
use App\Models\Folder;
use Carbon\Carbon;
use Illuminate\Database\Seeder;

class FoldersTableSeeder extends Seeder
{
    /**
     * Run the database seeds.
     *
     * @return void
     */
    public function run()
    {
        Folder::factory()->count(15)->create();
        $folders = Folder::all();

        foreach ($folders as $folder) {
            $folder->department()->increment('no_of_folders');
        }
    }
}