liwo/app/Notifications/DBNotification.php

<?php

namespace App\Notifications;

use Illuminate\Bus\Queueable;
use Illuminate\Notifications\Notification;

class DBNotification extends Notification
{
    use Queueable;

    public $message;

    /**
     * Create a new notification instance.
     *
     * @return void
     */
    public function __construct($message)
    {
        $this->message = $message;
    }

    /**
     * Get the notification's delivery channels.
     *
     * @param  mixed  $notifiable
     * @return array
     */
    public function via($notifiable)
    {
        return ['db'];
    }

    /**
     * Get the array representation of the notification.
     *
     * @param  mixed  $notifiable
     * @return array
     */
    public function toArray($notifiable)
    {
        return [
            'data' => $this->message['body'],
        ];
    }

    /**
     * Get the array for optional database field that added to original table.
     * @param $notifiable
     * @return array
     */
    public function toDatabaseOptional($notifiable)
    {
        return [
          'business_id' => $this->message['business_id'] ?? null
        ];
    }
}