一、创建通知

执行命令

php artisan make:notification NewMessageNotification

修改生成的文件：app/Notifications/NewMessageNotification.php

namespace App\Notifications;

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

class NewMessageNotification extends Notification
{
    use Queueable;

    public $message;

    public function __construct(Message $message)
    {
        $this->message = $message;
    }

    public function via($notifiable)
    {
        return ['database'];
    }
    public function toDatabase($notifiable)
    {
        return [
            'name' => $this->message->fromUser->name,
            'dialog' => $this->message->dialog_id,
        ];
    }

    public function toArray($notifiable)
    {
        return [
        ];
    }
}

二、发送通知

修改app/Repositories/MessageRepository.php

use App\Notifications\NewMessageNotification;

public function store($dialogId)
{
    $message = Message::where('dialog_id', $dialogId)->first();
    $toUserId = $message->from_user_id === user()->id ? $message->to_user_id : $message->from_user_id;
    $newMessage =  Message::create([
        'from_user_id' => user()->id,
        'to_user_id' => $toUserId,
        'content' => request('content'),
        'dialog_id' => $dialogId
    ]);
    return $newMessage->toUser->notify(new NewMessageNotification($newMessage));
}

三、查看通知

新建 resources/views/notifications/new_message_notification.blade.php

访问：http://127.0.0.1:8000/notifications 进行测试