How to use MQTT concept in FLASK REST API?

Question

I have a requirement where will have a POST api call ,read the json data from this and publish the messages to this topic "/home/floor_1/room" before publishing need to connect to the broker also and then return a success response . Project structure:

│   app.py
│   config.py
│   Dockerfile
│   requirement.txt
│
├───app_services
│   │   __init__.py
│   │
│   ├───controller
│   │   │   send_down_link.py
│   │   │   __init__.py
│   │
│   ├───models
│   │   │   __init__.py
│   │   │
│   │   ├───database
│   │   │   │   device.py

In app.py

from app_services import app

if __name__ == '__main__':
    app.run(host=app.config['HOST'], port=app.config['PORT'], debug=app.config['DEBUG'])

in app_service/ init .py

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_restful import Api
from flask_mqtt import Mqtt
from app_service.controller.send_down_link import SendDownlink

app = Flask(__name__)
db = SQLAlchemy(app)
mqtt = Mqtt(app)
api = Api(app)
api.add_resource(SendDownlink, "/api/t1/device/")

In controller/send_down_link.py:

class SendDownlink(Resource):
       def post(self):
         input_data =  request.get_json()
         message = input_data['message']

I want to publish this message to "/home/floor_1/room" topic . So i just want accommodate mqtt code in this 'post' method. Dont know how to work around it . Any suggestion ?

Answer 1

Given your stated goal is to just publish a message then the simplest way is to use the shortcut method provided by the Paho library that will handle all the connection and publication in a single call.

https://pypi.org/project/paho-mqtt/#publish-single-example

eg

import paho.mqtt.publish as publish

publish.single("home/floor_1/room", "payload", hostname="mqtt.eclipse.org")

ps Topics really shouldn't start with a leading / , it adds an unneeded null to the start of the topic tree and breaks things like Shared Subscriptions when you try and scale things later.