Laravel notifications does not store column data - laravel

Question

Notifications are not recording data in the database. I tried it with toDatabase and it also didn't work. Look:
<?php
namespace App\Notifications;
use App\User;
use Illuminate\Bus\Queueable;
use Illuminate\Contracts\Queue\ShouldQueue;
use Illuminate\Notifications\Messages\MailMessage;
use Illuminate\Notifications\Notification;
class NovoSeguidor extends Notification implements ShouldQueue
{
use Queueable;
private $user;
/**
* Create a new notification instance.
*
* #return void
*/
public function __construct(user $user)
{
$this->user = $user;
}
/**
* Get the notification's delivery channels.
*
* #param mixed $notifiable
* #return array
*/
public function via($notifiable)
{
return ['mail','database'];
}
/**
* Get the mail representation of the notification.
*
* #param mixed $notifiable
* #return \Illuminate\Notifications\Messages\MailMessage
*/
public function toMail($notifiable)
{
return (new MailMessage)
->line("Novo seguidor: {$this->user}")
->line('The introduction to the notification.')
->action('Notification Action', url('/'))
->line('Thank you for using our application!');
}
/**
* Get the array representation of the notification.
*
* #param mixed $notifiable
* #return array
*/
public function toArray($notifiable)
{
return [
'teste' => 'Hello',
];
}
}
My column data return [].
I tried both ways, both using toArray() and toDatabase(), both return an empty array.
I've tried everything and I don't see anything that could be causing it. Can anyone help me identify the problem?