Чат-платформа на основе django

Я создал платформу для общения в реальном времени на фреймворке Django с использованием каналов, но я не понимаю, почему она не сохраняет историю чата в базу данных. Поэтому я добавил несколько строк кода, но теперь он показывает undefined. Может ли кто-нибудь показать мне, как исправить код в моем consumers.py?

from django.contrib.auth import get_user_model
from channels.generic.websocket import WebsocketConsumer
from asgiref.sync import async_to_sync
from .models import Message
import json
User = get_user_model

class ChatConsumer(WebsocketConsumer):
    def fetch_messages(self, data):
        messages = Message.last_10_messages()
        content = {
            'messages': self.messages_to_json(messages)
        }
        self.send_messages(content)


    def new_message(self, data):
        author = data['from']
        author_user = User.objects.filter(username=author)[0]
        message = Message.objects.create(
            author=author_user,
            content=data['message'])

        content = {
            'command': 'new_message',
            'message': self.message_to_json(message)
        }
        return self.send_chat_message(content)



    def messages_to_json(self, messages):
        result = []
        for message in messages:
            result.append(self.message_to_json(message))
        return result

    def message_to_json(self, message):
        return {
            'author': message.author.username,
            'content': message.content,
            'timestamp': str(message.timestamp)
        }

    commands = {
        'fetch_messages': fetch_messages,
        'new_message': new_message
        }


    def connect(self):
        self.room = self.scope['url_route']['kwargs']['room']
        self.room_group_name = 'chat_%s' % self.room
        async_to_sync(self.channel_layer.group_add)(
            self.room_group_name,
            self.channel_name
        )
        self.accept()

    def disconnect(self, close_code):
        async_to_sync(self.channel_layer.group_discard)(
            self.room_group_name,
            self.channel_name
        )

    # Receive message from WebSocket
    def receive(self, text_data):
        data = json.loads(text_data)
        self.commands[data['command']](self, data)


    def send_chat_message(self, message):
        async_to_sync(self.channel_layer.group_send)(
            self.room_group_name,
            {
                'type': 'chat_message',
                'message': message
            }
        )

    def send_messages(self, message):
        self.send(text_data=json.dumps(message))
    
    def chat_message(self, event):
        message = event['message']
        self.send(text_data=json.dumps(message))

Вот мой пример кода view.py

def room(request, pk):
room = Room.objects.get(id=pk)
context = {
'room_name_json': mark_safe(json.dumps(pk)),
'username': mark_safe(json.dumps(request.user.username))
}
return render(request, 'base/room.html', context)

Это мой код Message sampe в models.py

class Message(models.Model):
author = models.ForeignKey(User, related_name='author_messages', on_delete=models.CASCADE)
content = models.TextField()
timestamp = models.DateTimeField(auto_now_add=True)

def __str__(self):
    return self.author.username

def last_10_messages():
    return Message.objects.order_by('-timestamp').all()[:10]

Ниже приведен мой код rome.html

{% extends 'main.html' %}
{% load static %}
{% block content %}
<textarea id="chat-log" cols="100" rows="20"></textarea><br>
<input id="chat-message-input" type="text" size="100"><br>
<input id="chat-message-submit" type="button" value="Send">
 
    


    <script src="{% static 'js/reconnecting-websocket.js' %}"></script>

    <script>
        // const room = JSON.parse(document.getElementById('pk').textContent);
        var roomName =  {{ room_name_json }};
        var username = {{ username }};

        const chatSocket = new WebSocket(
            'ws://'
            + window.location.host
            + '/ws/base/'
            + roomName
            + '/'
        );

        chatSocket.onmessage = function(e) {
            const data = JSON.parse(e.data);
            document.querySelector('#chat-log').value += (data.message + '\n');
        };

        chatSocket.onclose = function(e) {
            console.error('Chat socket closed unexpectedly');
        };

        document.querySelector('#chat-message-input').focus();
        document.querySelector('#chat-message-input').onkeyup = function(e) {
            if (e.keyCode === 13) {  // enter, return
                document.querySelector('#chat-message-submit').click();
            }
        };

        document.querySelector('#chat-message-submit').onclick = function(e) {
            const messageInputDom = document.querySelector('#chat-message-input');
            const message = messageInputDom.value;
            chatSocket.send(JSON.stringify({
                'message': message,
                'command': 'fetch_messages'
            }));
            messageInputDom.value = '';
        };
    </script>
    
{% endblock content %}