Laravel API Resource transform model to JSON response

<?php

// php artisan make:resource PostResource
namespace App\Http\Resources;

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

class PostResource extends JsonResource
{
    public function toArray(Request $request): array
    {
        return [
            'id'      => $this->id,
            'title'   => $this->title,
            'author'  => new UserResource($this->whenLoaded('author')),
            'created' => $this->created_at->toIso8601String(),
        ];
    }
}

// Controller
return PostResource::collection(Post::with('author')->paginate(15));