blue-twilight/app/ModelObservers/AlbumObserver.php

<?php

namespace App\ModelObservers;

use App\Album;

class AlbumObserver
{
    public function creating(Album $album)
    {
        // Re-generate the alias and path
        if (is_null($album->url_alias))
        {
            $album->generateAlias();
        }

        if (is_null($album->url_path))
        {
            $album->generateUrlPath();
        }
    }

    public function updating(Album $album)
    {
        // Re-generate the alias and path
        if (is_null($album->url_alias))
        {
            $album->generateAlias();
        }

        if (is_null($album->url_path))
        {
            $album->generateUrlPath();
        }
    }
}