Django channels without redis - redis

Question

I have a django app based on this tutorial that works perfectly. It uses Redis in the Channel layers
CHANNEL_LAYERS = {
'default': {
'BACKEND': 'channels_redis.core.RedisChannelLayer',
'CONFIG': {
"hosts": [('127.0.0.1', 6379)],
},
},
}
The problem I have is that my web hosting provider will not allow Redis (unless I pay ££££).
Every example that I can find uses Redis in this role. Is there an alternative I could use?

Answer 1

there are a few options.
you can run your channel layer on a different service to were the main instance runs. AWS ElastiCache or many other redis hosts out there.
There is also a RabbitMQ channel layer but if your hosting provider charges a lot for reddis i expect they will also charge a lot for this ... https://github.com/CJWorkbench/channels_rabbitmq/

Answer 2

It turned out that channels is a non-starter on an affordable web-hosting platform. So I reverted to using Ajax and long polling. My application is based on this Django Tutorial.
models.py
class Message(models.Model):
room_name = models.CharField(null=False, blank=False, max_length=50)
sender = models.CharField(null=False, blank=False, max_length=50, default='Sender username')
datetime = models.DateTimeField(null=True, auto_now_add=True)
type = models.IntegerField(null=True, blank=True)
text = models.CharField(null=False, blank=False, max_length=250, default='message text')
context = models.TextField(null=True, blank=True)
urls.py
urlpatterns = [
path('<str:partner_pk>/check-message', views.CheckMessage.as_view(), name="check-message"),
path('<str:partner_pk>/send-message/<str:chat_text>', views.SendMessage.as_view(), name="send-message"),
]
views.py
class CheckMessage(View):
"""Duo check message."""
def get(self, request, partner_pk):
"""Render the GET request."""
pair, room_name = sort_pair(partner_pk, request.user.pk)
partner = User.objects.get(pk=partner_pk)
profile = get_object_or_404(Profile, user=request.user)
message = Message.objects.filter(room_name=room_name, sender=partner.username).earliest('datetime')
context = {'type': -1}
context = json.loads(message.context)
context['sender'] = message.sender
context['datetime'] = message.datetime
context['message_type'] = message.type
context['text'] = message.text
context['seat'] = profile.seat
message.delete()
return JsonResponse(context, safe=False)
class SendMessage(View):
def get(self, request, partner_pk, chat_text):
message_type = app.MESSAGE_TYPES['chat']
send_message(request, partner_pk, message_type, text=chat_text, context={})
return JsonResponse({}, safe=False)
chat.js
window.setInterval(checkMessage, 3000);
function checkMessage () {
$.ajax(
{
type:"GET",
url: "check-message",
cache: false,
success: function(message) {
processMessage(message);
}
}
)
}
// Take action when a message is received
function processMessage(context) {
switch (context.message_type) {
case 0:
sendMessage(context)
functionOne()
break;
case 1:
sendMessage(context)
functionTwo()
break;
case 2:
sendMessage(context)
functionThree()
break;
}
}
// Send a message to chat
function sendMessage (context) {
if (context.sender != username) {
var messageObject = {
'username': context.sender,
'text': context.text,
};
displayChat(context);
}
}
// Display a chat message in the chat box.
function displayChat(context) {
if (context.text !== '') {
var today = new Date();
var hours = pad(today.getHours(), 2)
var minutes = pad(today.getMinutes(), 2)
var seconds = pad(today.getSeconds(), 2)
var time = hours + ":" + minutes + ":" + seconds;
var chat_log = document.getElementById("chat-log");
chat_log.value += ('('+time+') '+context.sender + ': ' + context.text + '\n');
chat_log.scrollTop = chat_log.scrollHeight;
}
}
//pad string with leading zeros
function pad(num, size) {
var s = num+"";
while (s.length < size) s = "0" + s;
return s;
}
// Call submit chat message if the user presses <return>.
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();
}
};
// Submit the chat message if the user clicks on 'Send'.
document.querySelector('#chat-message-submit').onclick = function (e) {
var messageField = document.querySelector('#chat-message-input'), text = messageField.value, chat_log = document.getElementById("chat-log");
context = {sender: username, text: messageField.value}
displayChat(context)
sendChat(messageField.value)
chat_log.scrollTop = chat_log.scrollHeight;
messageField.value = '';
};
// Call the send-chat view
function sendChat(chat_text) {
$.ajax(
{
type:"GET",
url: "send-message/"+chat_text,
cache: false,
}
)
}