main.py

import paho.mqtt.client as mqtt                                         #necessary imports
import json, os
from datetime import date, datetime
import time

  
""" callback function for connection """
def on_connect(client, userdata, flags, rc):                            #client method to connect
    if rc==0:
        client.connected_flag = True                                    #set flag

        # Subscribing to all the topics
        client.subscribe("cartrax/location/data")
        client.subscribe("cartrax/moisture_sensor/data")
        client.subscribe("cartrax/humidity_sensor/data")
        client.subscribe("cartrax/temperature_sensor/data")
        client.subscribe("cartrax/security/data")
        client.subscribe("cartrax/speedometer/data")
        
    else:
        print("Bad connection Returned code=",rc)                #if we can't connect

  
""" callback function for messages received """
def on_message( client, userdata, msg ):                                #client method to get messages from topic         
    topic = msg.topic                                                   #for use when we can't decode
    try:
        if topic == "cartrax/temperature_sensor/data":
            data = json.loads(msg.payload.decode("utf8"))                   #decode message
            Temperature = [0]
            moistureSensor = [0]  # addded
            Status = [1]
            Day = [2]
            Time_time = [3]
 
            print(f"Received from {topic} the following data --> {str(data)}\n")                                                #print the entire message just for fun
        
        if topic == "cartrax/moisture_sensor/data":
            data = json.loads(msg.payload.decode("utf8"))                   #decode message
            print(f"Received from {topic} the following data --> {str(data)}\n")
            
        if topic == "cartrax/humidity_sensor/data":
            dataHumidity = json.loads(msg.payload.decode("utf8"))  # decode message
            Humidity = dataHumidity[0]
            Status = dataHumidity[1]
            Day = dataHumidity[2]
            Time_time = dataHumidity[3]

            print(f"Received from {topic} the following data --> Humidity: {Humidity}, Status: {Status}, Day: {Day}, Time: {Time_time}\n")

    except Exception as e:
        print("Error:", e)
        print("Cannot decode data on topic {0}".format(topic))  # cannot decode; print the topic for the non-decodable message
            
        if topic == "cartrax/speedometer/data":
            dataSpeed = json.loads(msg.payload.decode("utf8"))              #decode message
            Speed = dataSpeed[0]
            Status = dataSpeed[1]
            Day = dataSpeed[2]
            Time_time = dataSpeed[3]
            
            print(f"Received from {topic} the following data --> {str(dataSpeed)}\n")                                           #prints entire message
            
            
    except:
        print ("Cannot decode data on topic {0}".format(topic))         #cannot decode; print the topic for the non-decodable message



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

client.connect("broker.hivemq.com", 1883)                             #connect to the broker on an appropriate port
      
client.loop_forever()                                                   #keep looping forever (allows realtime subscription)