New chat message notification Django Channels

Question

I've got Django Channels 2.1.2 set up in my Django app by following a tutorial and now need to set up a notification system for new messages. I want to do this in the simplest way possible.

I can do it via browser push notifications, but I don't want to do it like that. I want it to be like Stack Overflow, where there is a red number representing the instance of a new message.

One answer on here said

For notifications you only need two models: User and Notification. On connect set the scope to the currently authenticated user. Set up a post_save signal on your Notification model to trigger a consumer method to message the notification object's user. –

I am struggling to wrap my head around what this would look like, I already have a User model but no Notification one.

The chat is between only 2 users, it is not a chat room but more of a chat thread. The 2 html templates are inbox.html and thread.html

Appreciate any help!

My Django Channels code is below!

consumers.py

class ChatConsumer(AsyncConsumer):
    async def websocket_connect(self, event):
        print('connected', event)

        other_user = self.scope['url_route']['kwargs']['username']
        me = self.scope['user']
        #print(other_user, me)
        thread_obj = await self.get_thread(me, other_user)
        self.thread_obj = thread_obj
        chat_room = f"thread_{thread_obj.id}"
        self.chat_room = chat_room
        # below creates the chatroom
        await self.channel_layer.group_add(
            chat_room,
            self.channel_name
        )

        await self.send({
            "type": "websocket.accept"
        })

    async def websocket_receive(self, event):
        # when a message is recieved from the websocket
        print("receive", event)

        message_type = event.get('type', None)  #check message type, act accordingly
        if message_type == "notification_read":
            # Update the notification read status flag in Notification model.
            notification = Notification.object.get(id=notification_id)
            notification.notification_read = True
            notification.save()  #commit to DB
            print("notification read")

        front_text = event.get('text', None)
        if front_text is not None:
            loaded_dict_data = json.loads(front_text)
            msg =  loaded_dict_data.get('message')
            user = self.scope['user']
            username = 'default'
            if user.is_authenticated:
                username = user.username
            myResponse = {
                'message': msg,
                'username': username,
            }
            await self.create_chat_message(user, msg)

            # broadcasts the message event to be sent, the group send layer
            # triggers the chat_message function for all of the group (chat_room)
            await self.channel_layer.group_send(
                self.chat_room,
                {
                    'type': 'chat_message',
                    'text': json.dumps(myResponse)
                }
            )
    # chat_method is a custom method name that we made
    async def chat_message(self, event):
        # sends the actual message
        await self.send({
                'type': 'websocket.send',
                'text': event['text']
        })

    async def websocket_disconnect(self, event):
        # when the socket disconnects
        print('disconnected', event)

    @database_sync_to_async
    def get_thread(self, user, other_username):
        return Thread.objects.get_or_new(user, other_username)[0]

    @database_sync_to_async
    def create_chat_message(self, me, msg):
        thread_obj = self.thread_obj
        return ChatMessage.objects.create(thread=thread_obj, user=me, message=msg)

manager

class ThreadManager(models.Manager):
    def by_user(self, user):
        qlookup = Q(first=user) | Q(second=user)
        qlookup2 = Q(first=user) & Q(second=user)
        qs = self.get_queryset().filter(qlookup).exclude(qlookup2).distinct()
        return qs

    # method to grab the thread for the 2 users
    def get_or_new(self, user, other_username): # get_or_create
        username = user.username
        if username == other_username:
            return None, None
        # looks based off of either username
        qlookup1 = Q(first__username=username) & Q(second__username=other_username)
        qlookup2 = Q(first__username=other_username) & Q(second__username=username)
        qs = self.get_queryset().filter(qlookup1 | qlookup2).distinct()
        if qs.count() == 1:
            return qs.first(), False
        elif qs.count() > 1:
            return qs.order_by('timestamp').first(), False
        else:
            Klass = user.__class__
            try:
                user2 = Klass.objects.get(username=other_username)
            except Klass.DoesNotExist:
                user2 = None
            if user != user2:
                obj = self.model(
                        first=user,
                        second=user2
                    )
                obj.save()
                return obj, True
            return None, False

models.py

class Thread(models.Model):
    first        = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name='chat_thread_first')
    second       = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE, related_name='chat_thread_second')
    updated      = models.DateTimeField(auto_now=True)
    timestamp    = models.DateTimeField(auto_now_add=True)

    objects      = ThreadManager()

    def __str__(self):
        return f'{self.id}'

    @property
    def room_group_name(self):
        return f'chat_{self.id}'

    def broadcast(self, msg=None):
        if msg is not None:
            broadcast_msg_to_chat(msg, group_name=self.room_group_name, user='admin')
            return True
        return False

class ChatMessage(models.Model):
    thread      = models.ForeignKey(Thread, null=True, blank=True, on_delete=models.SET_NULL)
    user        = models.ForeignKey(settings.AUTH_USER_MODEL, verbose_name='sender', on_delete=models.CASCADE)
    message     = models.TextField()
    timestamp   = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return f'{self.id}'

class Notification(models.Model):
    notification_user = models.ForeignKey(User, on_delete=models.CASCADE)
    notification_chat = models.ForeignKey(ChatMessage, on_delete=models.CASCADE)
    notification_read = models.BooleanField(default=False)

    def __str__(self):
        return f'{self.id}'

views.py

class InboxView(LoginRequiredMixin, ListView):
    template_name = 'chat/inbox.html'
    context_object_name = 'threads'
    def get_queryset(self):
        return Thread.objects.by_user(self.request.user).exclude(chatmessage__isnull=True).order_by('timestamp')
        # by_user(self.request.user)

class ThreadView(LoginRequiredMixin, FormMixin, DetailView):
    template_name = 'chat/thread.html'
    form_class = ComposeForm
    success_url = '#'

    def get_queryset(self):
        return Thread.objects.by_user(self.request.user)

    def get_object(self):
        other_username  = self.kwargs.get("username")
        obj, created    = Thread.objects.get_or_new(self.request.user, other_username)
        if obj == None:
            raise Http404
        return obj

    def get_context_data(self, **kwargs):
        context = super().get_context_data(**kwargs)
        context['form'] = self.get_form()
        return context

    def post(self, request, *args, **kwargs):
        if not request.user.is_authenticated:
            return HttpResponseForbidden()
        self.object = self.get_object()
        form = self.get_form()
        if form.is_valid():
            return self.form_valid(form)
        else:
            return self.form_invalid(form)

    def form_valid(self, form):
        thread = self.get_object()
        user = self.request.user
        message = form.cleaned_data.get("message")
        ChatMessage.objects.create(user=user, thread=thread, message=message)
        return super().form_valid(form)

thread.html

{% block head %}
<title>Chat</title>
<script src="{% static '/channels/js/websocketbridge.js' %}" type="text/javascript"></script>
{% endblock %}


    {% block content %}
<script>
  $(#notification-element).on("click", function(){
      data = {"type":"notification_read", "username": username, "notification_id": notification_id};
      socket.send(JSON.stringify(data));
  });
</script>

<!-- back to inbox button with notification example -->
        <a class="btn btn-light" id="notification_id" href="{% url 'chat:inbox' %}">Back to Inbox</a>

    <div class="msg_history">
          {% for chat in object.chatmessage_set.all %}
          {% if chat.user == user %}
          <div class="outgoing_msg">
            <div class="outgoing_msg_img"> <img src="{{ chat.user.profile.image.url }}"> </div>
            <div class="sent_msg">
              <p>{{ chat.message }}</p>
              <span class="time_date"> {{ chat.timestamp }}</span>
            </div>
          </div>
          {% else %}
          <div class="incoming_msg">
            <div class="incoming_msg_img"> <img src="{{ chat.user.profile.image.url }}"> </div>
            <div class="received_msg">
              <div class="received_withd_msg">
                <p>{{ chat.message }}</p>
                <span class="time_date"> {{ chat.timestamp }}</span>
              </div>
            </div>
          </div>
          {% endif %}
          {% endfor %}
        </div>
        <div class="type_msg">
          <div class="input_msg_write">
            <!-- text input / write message form -->
            <form id='form' method='POST'>
              {% csrf_token %}
              <input type='hidden' id='myUsername' value='{{ user.username }}' />
              {{ form.as_p }}
              <center><button type="submit" class='btn btn-success disabled' value="Send">Send</button></center>
            </form>
          </div>
        </div>
      </div>
    </div>
  </div>
</div>
{% endblock %}

{% block script %}

<script src='https://cdnjs.cloudflare.com/ajax/libs/reconnecting-websocket/1.0.0/reconnecting-websocket.js'></script>

<script>
  // websocket scripts - client side*
  var loc = window.location
  var formData = $("#form")
  var msgInput = $("#id_message")
  var chatHolder = $('#chat-items')
  var me = $('#myUsername').val()

  var wsStart = 'ws://'
  if (loc.protocol == 'https:') {
    wsStart = 'wss://'
  }
  var endpoint = wsStart + loc.host + loc.pathname
  var socket = new ReconnectingWebSocket(endpoint)

  // below is the message I am receiving
  socket.onmessage = function(e) {
    console.log("message", e)
    var data = JSON.parse(event.data);
    // Find the notification icon/button/whatever and show a red dot, add the notification_id to element as id or data attribute.
    var chatDataMsg = JSON.parse(e.data)
    chatHolder.append('<li>' + chatDataMsg.message + ' from ' + chatDataMsg.username + '</li>')
  }
  // below is the message I am sending
  socket.onopen = function(e) {
    console.log("open", e)
    formData.submit(function(event) {
      event.preventDefault()
      var msgText = msgInput.val()

      var finalData = {
        'message': msgText
      }
      socket.send(JSON.stringify(finalData))
      formData[0].reset()
    })
  }
  socket.onerror = function(e) {
    console.log("error", e)
  }
  socket.onclose = function(e) {
    console.log("close", e)
  }
</script>

<script>
  document.addEventListener('DOMContentLoaded', function() {
    const webSocketBridge = new channels.WebSocketBridge();
    webSocketBridge.connect('/ws');
    webSocketBridge.listen(function(action, stream) {
      console.log("RESPONSE:", action);
    })
    document.ws = webSocketBridge; /* for debugging */
  })
</script>

{% endblock %}

Answer 1

One easy way to implement a notification system can be:

When you want to show a new message, manipulate HTML using JS as soon as you get a message on the websocket. And whenever the element has been interacted with, which means the user has read the notification, send a message back to server using the websocket.

Your Notification can have ForeignKeys to user and the message along with a BooleanField for read status. Whenever you are sending the message to the user, you should append the notification_id along the message,

#consumer.py
async def websocket_receive(self, event):
        # when a message is received from the websocket
        print("receive", event)

        message_type = event.get('type', None)  #check message type, act accordingly
        if message_type == "notification_read":
             # Update the notification read status flag in Notification model.
             notification = Notification.object.get(id=notification_id)
             notification.notification_read = True
             notification.save()  #commit to DB
             print("notification read")

        front_text = event.get('text', None)
        if front_text is not None:
            loaded_dict_data = json.loads(front_text)
            msg =  loaded_dict_data.get('message')
            user = self.scope['user']
            username = 'default'
            if user.is_authenticated:
                username = user.username
            myResponse = {
                'message': msg,
                'username': username,
                'notification': notification_id  # send a unique identifier for the notification
            }
            ...

On the client side,

// thread.html
socket.onmessage = function(e) {
    var data = JSON.parse(event.data);
    // Find the notification icon/button/whatever and show a red dot, add the notification_id to element as id or data attribute.
}
...

$(#notification-element).on("click", function(){
    data = {"type":"notification_read", "username": username, "notification_id": notification_id};
    socket.send(JSON.stringify(data));
});

You can mark individual/all unread notifications as read according to your need.

I did something similar for a training project, you can check that out for ideas. Github link.