如何在python中获取mqtt连接的消息数据

Question

I am using the mqtt lib in Python to send and receive messages via mqtt. At first I simply used this code:

import paho.mqtt.client as mqtt


def on_connect(client, userdata, flags, rc):
  print("Connected with result code " + str(rc))
  client.subscribe("test/temperature2")

def on_message(client, userdata, msg):
  print(msg.topic + " " + str(msg.payload))



client = mqtt.Client()
client.on_connect = on_connect
client.on_message = on_message
client.connect("localhost", 1883, 60)

client.loop_forever()

The example code works fine. Now I want to actually work with the message but, I don't know how to access the message. Sure msg.payload is printed, but some how I can't access it from outside the function. I tried to alternate the code a bit, but it didn't help. Eg when I try to return the value msg.payload to client.on_message I only get some address I think like a huge HEX Value. Can anyone tell me how to read the value outside the function or how to return this value?

Thanks!

Answer 1

You can create a global variable and append your msg.payload . After that you can use them by iterating over that list in another thread.

payloads = []
def on_message(client, userdata, msg):
    payloads.append(msg.payload)
    print(msg.topic + " " + str(msg.payload))

# ...

def funct():
    print payloads

thread.start_new_thread(funct, ())