python - How to use paho mqtt client in django?

Question

I am writing a django application which should act as MQTT publisher and as a subscriber.

Where should I start the paho client and run loop_forever() function.

Should it be in wsgi.py ?

Answer 1

Update:

If you need Django running in multiple threads then to publish messages from your Django app you can use helper functions from Publish module of Paho - https://eclipse.org/paho/clients/python/docs/#id17 You don't need to create an instance of mqtt client and start a loop in this case. And to subscribe to some topic consider running mqtt client as a standalone script and import there needed modules of your Django app (and don't forget to setup the Django environment in the script).

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The answer below is good only if you run Django in a single thread, which is not usual in production.

Create mqtt.py in your application folder and put all related code there. For example:

import paho.mqtt.client as mqtt

def on_connect(client, userdata, rc):
    client.subscribe("$SYS/#")

def on_message(client, userdata, msg):
    # Do something
    pass

client = mqtt.Client()
client.on_connect = on_connect
client.on_message = on_message

client.connect("iot.eclipse.org", 1883, 60)

Don't call loop_forever() here!

Then in your application __init__.py call loop_start():

from . import mqtt

mqtt.client.loop_start()

Using loop_start() instead of loop_forever() will give you not blocking background thread.