how to integrate paho python client with Django
Nam Usr
from this SO question, I implemented a subscriber client in my Django project as following:
in mqtt.py, I create a client and connect to a local broker and subscribe to a topic.
#myapp/mqtt.py: import paho.mqtt.client as paho import json import django django.setup() from .models import Temperature, Turbidity, Refined_fuels, Crude_oil from datetime import datetime # The callback for when the client receives a CONNACK response from the server. def on_connect(client, userdata, flags, rc): print("CONNACK received with code %d." % (rc)) client.subscribe("sensor/temp", qos=0) def on_subscribe(client, userdata, mid, granted_qos): print("Subscribed: "+str(mid)+" "+str(granted_qos)) # The callback for when a PUBLISH message is received from the server. def on_message(client, userdata, msg): print(msg.topic+", "+'QOS: ' +str(msg.qos)+",\n"+str(msg.payload, 'utf-8')) message_dict = json.loads(msg.payload) now = datetime.now() captured_timestamp = datetime.utcfromtimestamp(int(message_dict['Timestamp'])).strftime('%Y-%m-%d %H:%M:%S') print('timestamp: ', captured_timestamp ) if message_dict['Temperature'] and message_dict['D850'] and message_dict['D280']: temp = Temperature(captured_timestamp=captured_timestamp, data=message_dict['Temperature'], received_timestamp=now) temp.save() refined_fuels = Refined_fuels(captured_timestamp=captured_timestamp, data=float(message_dict['D850']), received_timestamp=now) refined_fuels.save() crude_oil = Crude_oil(captured_timestamp=captured_timestamp, data=float(message_dict['D280']), received_timestamp=now) crude_oil.save() # defining client client = paho.Client(client_id="testSubscriber", clean_session=True, userdata=None, protocol=paho.MQTTv311) # adding callbacks to client client.on_connect = on_connect client.on_subscribe = on_subscribe client.on_message = on_message client.connect(host="localhost", port=1883, keepalive=60, bind_address="" )in __init__.py I call the loop_start() of client:
# myapp/__init__.py from . import mqtt mqtt.client.loop_start()For publisher client I used paho C client. and for broker I used hivemq-4.5.1 enterprise trial version. And, I'm running the project on ubuntu 18.04.
now, When I run the Django server(python manage.py runserver), it keeps calling the on_connect() method and continues on_connect() method, But the server is not running and I cant access the project from localhost:8000.
this is the django error before the on_connect() and on_subscribe() methods keep printing their messages:
Exception in thread django-main-thread:
Traceback (most recent call last):
File "/usr/local/lib/python3.8/threading.py", line 932, in _bootstrap_inner
self.run()
File "/usr/local/lib/python3.8/threading.py", line 870, in run
self._target(*self._args, **self._kwargs)
File "/home/shahriar/webapp/venv/lib/python3.8/site-packages/django/utils/autoreload.py", line 53, in wrapper
fn(*args, **kwargs)
File "/home/shahriar/webapp/venv/lib/python3.8/site-packages/django/core/management/commands/runserver.py", line 110, in inner_run
autoreload.raise_last_exception()
File "/home/shahriar/webapp/venv/lib/python3.8/site-packages/django/utils/autoreload.py", line 76, in raise_last_exception
raise _exception[1]
File "/home/shahriar/webapp/venv/lib/python3.8/site-packages/django/core/management/init.py", line 357, in execute
autoreload.check_errors(django.setup)()
File "/home/shahriar/webapp/venv/lib/python3.8/site-packages/django/utils/autoreload.py", line 53, in wrapper
fn(*args, **kwargs)
File "/home/shahriar/webapp/venv/lib/python3.8/site-packages/django/init.py", line 24, in setup
apps.populate(settings.INSTALLED_APPS)
File "/home/shahriar/webapp/venv/lib/python3.8/site-packages/django/apps/registry.py", line 94, in populate
raise ImproperlyConfigured(
django.core.exceptions.ImproperlyConfigured: Application labels aren't unique, duplicates: graphs
and this is the broker log that is ok and shows no error:
2021-03-01 10:06:38,056 INFO - Received PUBLISH from client 'testPublisher' for topic 'sensor/temp': Payload: '{ "Timestamp": 1609446782, "Temperature": "30.13", "D850": "102.48", "D280": "4845.83" }', QoS: '2', Retained: 'false'
2021-03-01 10:06:38,058 INFO - Sent PUBREC to client 'testPublisher': Reason Code: 'SUCCESS'
2021-03-01 10:06:38,059 INFO - Sent PUBLISH to client 'testSubscriber' on topic 'sensor/temp': Payload: '{ "Timestamp": 1609446782, "Temperature": "30.13", "D850": "102.48", "D280": "4845.83" }', QoS: '0', Retained: 'false'
2021-03-01 10:06:38,075 INFO - Received CONNECT from client 'testSubscriber': Protocol version: 'V_3_1_1', Clean Start: 'true', Session Expiry Interval: '0'
2021-03-01 10:06:38,207 INFO - Sent CONNACK to client 'testSubscriber': Reason Code: 'SUCCESS', Session Present: 'false'
2021-03-01 10:06:38,209 INFO - Received SUBSCRIBE from client 'testSubscriber': Topics: { [Topic: 'sensor/temp', QoS: '0'] }
2021-03-01 10:06:38,209 INFO - Sent SUBACK to client 'testSubscriber': Suback Reason Codes: { [Reason Code: 'GRANTED_QOS_0'] }
2021-03-01 10:06:39,056 INFO - Received PUBREL from client 'testPublisher': Reason Code: 'SUCCESS'
2021-03-01 10:06:39,057 INFO - Sent PUBCOMP to client 'testPublisher': Reason Code: 'SUCCESS'
2021-03-01 10:06:39,131 INFO - Received CONNECT from client 'testSubscriber': Protocol version: 'V_3_1_1', Clean Start: 'true', Session Expiry Interval: '0'
2021-03-01 10:06:39,158 INFO - Received PUBLISH from client 'testPublisher' for topic 'sensor/temp': Payload: '{ "Timestamp": 1609446783, "Temperature": "30.13", "D850": "102.48", "D280": "4845.83" }', QoS: '2', Retained: 'false'
2021-03-01 10:06:39,161 INFO - Sent PUBREC to client 'testPublisher': Reason Code: 'SUCCESS'
2021-03-01 10:06:39,200 INFO - Sent CONNACK to client 'testSubscriber': Reason Code: 'SUCCESS', Session Present: 'false'
2021-03-01 10:06:39,201 INFO - Received SUBSCRIBE from client 'testSubscriber': Topics: { [Topic: 'sensor/temp', QoS: '0'] }
2021-03-01 10:06:39,203 INFO - Sent SUBACK to client 'testSubscriber': Suback Reason Codes: { [Reason Code: 'GRANTED_QOS_0'] }
2021-03-01 10:06:40,162 INFO - Received PUBREL from client 'testPublisher': Reason Code: 'SUCCESS'
2021-03-01 10:06:40,162 INFO - Sent PUBCOMP to client 'testPublisher': Reason Code: 'SUCCESS'
2021-03-01 10:06:40,262 INFO - Received PUBLISH from client 'testPublisher' for topic 'sensor/temp': Payload: '{ "Timestamp": 1609446784, "Temperature": "30.13", "D850": "102.48", "D280": "4845.83" }', QoS: '2', Retained: 'false'
now the question is that, is the implementation of paho python client in Django wrong?
Since I wanted to store messages in DB, I imported the models in mqtt.py and that caused an error:
raise AppRegistryNotReady("Apps aren't loaded yet.")
django.core.exceptions.AppRegistryNotReady: Apps aren't loaded yet.
to over come that. I put
import django django.setup()before importing models in mqtt.py and that solved the problem.
to the best of my knowledge, it starts the app which mqtt.py is inside of it before the main app. So the django see two instance of that app and throws this error:
raise ImproperlyConfigured(
django.core.exceptions.ImproperlyConfigured: Application labels aren't unique, duplicates: graphs
So, I understand that my implementation is wrong. but how to correct it?