koel/app/Http/Resources/PlaylistResource.php

<?php

namespace App\Http\Resources;

use App\Models\Playlist;
use App\Models\User;
use Illuminate\Http\Resources\Json\JsonResource;

class PlaylistResource extends JsonResource
{
    public const JSON_STRUCTURE = [
        'type',
        'id',
        'name',
        'folder_id',
        'user_id',
        'is_smart',
        'rules',
        'own_songs_only',
        'created_at',
    ];

    public function __construct(private Playlist $playlist)
    {
        parent::__construct($playlist);
    }

    /** @return array<mixed> */
    public function toArray($request): array
    {
        /** @var User $user */
        $user = $request->user() ?? $this->playlist->user;

        return [
            'type' => 'playlists',
            'id' => $this->playlist->id,
            'name' => $this->playlist->name,
            'folder_id' => $this->playlist->getFolderId($user),
            'user_id' => $this->playlist->user_id,
            'is_smart' => $this->playlist->is_smart,
            'is_collaborative' => $this->playlist->is_collaborative,
            'rules' => $this->playlist->rules,
            'cover' => $this->playlist->cover,
            'own_songs_only' => $this->playlist->own_songs_only,
            'created_at' => $this->playlist->created_at,
        ];
    }
}