MQTT物聯網智能插件 Python

Question

我是物聯網的新手，我有一個針對我大學的代碼練習。 我不知道如何連接此腳本才能連接到 MQTT 並正常運行。

如何與 MQTT 連接？ 腳本如下：

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)

我收到以下錯誤：

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()

您需要在創建Client實例時添加括號。

TypeError：未綁定方法 connect() 必須使用 Client 實例作為第一個參數調用（改為獲取 str 實例）

它說未綁定的事實表明您沒有創建實例。 相反， self.client只是Client class本身的另一個名稱。