LaravelApp/app/Http/Resources/AttachmentResource.php

<?php

namespace App\Http\Resources;

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

class AttachmentResource extends JsonResource
{
    public function toArray(Request $request): array
    {
        return [
            'id' => $this->id,
            'filename' => $this->filename,
            'filepath' => $this->filepath,
            'mime_type' => $this->mime_type,
            'size' => $this->size,
            'size_human' => $this->formatBytes($this->size),
            'created_at' => $this->created_at->toISOString(),
        ];
    }

    private function formatBytes($bytes, $precision = 2)
    {
        $units = ['B', 'KB', 'MB', 'GB', 'TB'];
        
        for ($i = 0; $bytes > 1024 && $i < count($units) - 1; $i++) {
            $bytes /= 1024;
        }
        
        return round($bytes, $precision) . ' ' . $units[$i];
    }
}