Using private channels on Laravel Echo

Hello everybody,

Actually I am still working on my private messaging app.

To load new notifications, I would like to use a PrivateChannel.

This is what I'm doing at the moment:

bootstrap.js

import Echo from 'laravel-echo'

window.io = require('socket.io-client');

window.Echo = new Echo({
    broadcaster: 'socket.io',
    host: window.location.hostname + ':6001'
});

window.Echo.private('conversation.${messageId}')
.listen('MessageCreated', (e) => {
    console.log(e);
});

MessageChannel.php

<?php

namespace App\Broadcasting;

use App\User;
use App\Message;
use Illuminate\Support\Facades\Log;

class MessageChannel
{
    /**
     * Create a new channel instance.
     *
     * @return void
     */
    public function __construct()
    {
        //
    }
    
    
    /**
     * @param \App\User    $user
     * @param \App\Message $message
     *
     * @return bool
     */public function join(User $user, Message $message)
    {
        return $user->id === $message->user_id;
    }
}

MessageCreated.php

<?php

namespace App\Events;

use Illuminate\Broadcasting\Channel;
use Illuminate\Queue\SerializesModels;
use Illuminate\Broadcasting\PrivateChannel;
use Illuminate\Broadcasting\PresenceChannel;
use Illuminate\Foundation\Events\Dispatchable;
use Illuminate\Broadcasting\InteractsWithSockets;
use Illuminate\Contracts\Broadcasting\ShouldBroadcast;
use Cmgmyr\Messenger\Models\Message;

class MessageCreated implements ShouldBroadcast
{
    use Dispatchable, InteractsWithSockets, SerializesModels;
    
    public $message;
    
    /**
     * MessageCreated constructor.
     *
     * @param \App\Message $message
     */
    public function __construct(Message $message)
    {
        $this->message = $message;
    }

    /**
     * Get the channels the event should broadcast on.
     *
     * @return \Illuminate\Broadcasting\Channel|array
     */
    public function broadcastOn()
    {
        return new PrivateChannel('conversation.'.$this->message->id);
    }
}

channels.php

Broadcast::channel('conversation.{messageId}', function($user, $messageId){
    return Auth::check(); //has to be improved. Check, whether the user is in recipients list
});

web.php (test route)

Route::get('test', function(){
    $message = App\Message::find(1);
    broadcast(new \App\Events\MessageCreated($message));
});

Now I'm getting this in my Echo console:

[13:44:07] - Sending auth request to: https://test.app/broadcasting/auth

[13:44:10] - Do63uEo-ePk8Nh9jAAC0 authenticated for: private-conversation.${messageId}
[13:44:10] - Do63uEo-ePk8Nh9jAAC0 joined channel: private-conversation.${messageId}

I got this from https://laravel.com/docs/5.7/broadcasting -> Listening For Event Broadcasts

Echo.private(`order.${orderId}`)
    .listen('ShippingStatusUpdated', (e) => {
        console.log(e.update);
    });

But where does Echo.private get ${orderId} from in this example?