如何通过 mqtt 发送包含不同数据类型的消息？

Question

I am trying to send a message to the broker over a websocket. The message contains numbers that represent sensor data, so the message can be a mix of integers and floats. When I run the code I get TypeError: payload must be a string, bytearray, int, float or None. How can the code be changed to send a message containing integers and floats? I am using CloudMQTT as a broker.

Full code:

import paho.mqtt.client as mqtt
import time

client = mqtt.Client()
client.username_pw_set("User", "Password")
client.connect("Server", "Port")

num_one = 5.83
num_two = -12.46
num_three = 2

message = (num_one, num_two, num_three)

while True:
    client.publish("topic", message)
    time.sleep(1)

Answer 1

It looks like your problem is that the message you're sending is a tuple. You probably want

message = (num_one, num_two, num_three)
message = ''.join([str(x) for x in message])

This will convert each number to a string, then join them to a single string.

Answer 2

Choose an appropriate binary or text based format for your message, and encode your structure in that format. It will then either be a bytearray or string.

Unless there's a good reason to roll your own format, I'd suggest SenML as it is barely more complex than most non-standard JSON formats, but is sufficiently standardised you can at least say you're trying to be compatible with other applications.