MQTT物联网智能插件 Python

Question

I am totally new in IoT and I have a code exercise for my university. I don't know how to connect this script in order to connect to MQTT and run without errors.

How can I connect with MQTT? The script is the following:

import paho.mqtt.client as mqtt
import ssl
import os
import sys

import matplotlib.pyplot as plt
from matplotlib.widgets import Button
from threading import Timer
from datetime import datetime

class IoTExample:
    def __init__(self):
        self._establish_mqtt_connection()

    def start(self):
        self.client.loop_forever() 
    
    def disconnect(self, args=None):
        self.client.disconnect()

    def _establish_mqtt_connection(self):
        self.client = mqtt.Client
        self.client.on_log = self._on_log
        client.username_pw_set('iotlesson', 'YGK0tx5pbtkK2WkCBvJlJWCg')
        self.client.connect('phoenix.medialab.ntua.gr', 8883)
        client.subscribe('hscnl/hscnl02/state/ZWaveNode005_Switch/state')
        self.client.publish('hscnl/hscnl02/sendcommand/ZWaveNode005_Switch', 'ON')
        self.client.loop_forever()

    def _on_connect(self, client, userdata, flags, rc):
        self.client.on_connect = self._on_connect

    def _on_message(self, client, userdata, msg):
        self.client.on_message = self.on_message
        print(msg.topic+' '+str(msg.payload))

    def _on_log(self, client, userdata, level, buf):
        self.client.on_log = self._on_log
        print('log: ', buf)

try:
    iot_example = IoTExample()
    iot_example.start()
except KeyboardInterrupt:
    print('Interrupted')
    try:
        iot_example.disconnect()
        sys.exit(0)
    except SystemExit:
        os._exit(0)

I got the following errors:

python /home/mina/paho.mqtt.python/iot_example.py
Traceback (most recent call last):
  File "/home/mina/paho.mqtt.python/iot_example.py", line 41, in <module>
    iot_example = IoTExample()
  File "/home/mina/paho.mqtt.python/iot_example.py", line 13, in __init__
    self._establish_mqtt_connection()
  File "/home/mina/paho.mqtt.python/iot_example.py", line 24, in _establish_mqtt_connection
    self.client.connect('phoenix.medialab.ntua.gr', 8883)
TypeError: unbound method connect() must be called with Client instance as first argument (got str instance instead)

Answer 1

   def _establish_mqtt_connection(self):
        self.client = mqtt.Client()

You need to add parentheses when you create the Client instance.

TypeError: unbound method connect() must be called with Client instance as first argument (got str instance instead)

The fact that it says unbound is a clue that you didn't create an instance. Instead, self.client was just another name for the Client class itself.