OOP 中的 Python MQTT 回调

Question

我目前正在尝试在面向对象的上下文中使用 Python3 中的 paho mqtt 库。 但是，由于某种原因，回调函数没有被调用。

import paho.mqtt.client as mqtt
import time
import logging

logger = logging.getLogger("IDS_LOGGER.refining")
logging.basicConfig(level=logging.INFO)

class refiner(object):


def __init__(self,configpath="./sampleconfig.xml"):
    try:
        self.CONFIGPATH = configpath
        self.BROKER_IP = "localhost"

        self.parse_config()
        self.client = mqtt.Client()
        self.client.on_connect = self.on_connect
        self.client.on_message = self.on_message
        self.client.connect(self.BROKER_IP)
        logging.info("Connected to {0}, starting MQTT loop".format(self.BROKER_IP))
        self.client.loop_forever()
    except Exception as e:
        print("error")


def on_message(self,client,userdata,msg):
    """MQTT Callback function for handling received messages"""
    print("message received!")


def on_connect(self,client,userdata,msg):
    print("connected!")
    self.client.subscribe("TRACED")

为什么？

Answer 1

将 on_connect() 定义替换为:

def on_connect(self, client, userdata, flags, rc):
        print("connected!")
        self.client.subscribe("TRACED")

此外，出于调试目的，请考虑在异常处理程序中打印实际异常，而不是仅打印“error”:

    try:
        ...
    except Exception as e:
        print(e)

通过上述修复，我通过连接到 test.mosquitto.org 测试了您的代码:

class refiner(object):

    def __init__(self):
        try:
            self.BROKER_IP = "test.mosquitto.org"
            self.client = mqtt.Client()
            self.client.on_connect = self.on_connect
            self.client.connect(self.BROKER_IP, 1883, 60)
            logging.info("Connected to {0}, starting MQTT loop".format(self.BROKER_IP))
            self.client.loop_forever()
        except Exception as e:
            print(e)

    def on_connect(self, client, userdata, flags, rc):
        print("connected!")
        self.client.subscribe("TRACED")

x = refiner()

它成功输出:

INFO:root:Connected to test.mosquitto.org, starting MQTT loop
connected!