python mqtt訂閱多條消息

Question

我確實發布了多條消息：

#!/usr/bin/env python3

import paho.mqtt.publish as publish

topic1 = "testtopic/topic1"
topic2 = "testtopic/topic2"

val1 = b'54.8'
val2 = b'598.45'
val3 = b'4813.9'

msgs = [(topic1, val1),
        (topic1, val2),
        (topic2, val3)]

publish.multiple(msgs, hostname="localhost")

訂閱它時

#!/usr/bin/env python3

import paho.mqtt.client as mqtt
import json

broker_url = "localhost"
broker_port = 1883

def on_connect(client, userdata, flags, rc):
    print("Connected With Result Code: {}".format(rc))
def on_disconnect(client, userdata, rc):
    print("Client Got Disconnected")
def on_message(client, userdata, message):
    msg = json.loads(message.payload.decode())
    print("Message Recieved: " + str(msg))
    
client = mqtt.Client()
client.connect(broker_url, broker_port)

client.on_connect = on_connect
client.on_message = on_message
client.on_disconnect = on_disconnect

topic = "testtopic/#"

client.subscribe(topic, qos=0)

client.loop_forever()

我明白了

Connected With Result Code: 0
Message Recieved: 54.8
Message Recieved: 598.45
Message Recieved: 4813.9

我如何將三個值分配給單個變量（例如 value1 = 54.8、value2 = 598.45、value3 = 598.45）以便能夠像進行一些計算或將其保存到文件一樣使用它們。

Answer 1

您可以使用下面這樣的 JSON 格式..

#!/usr/bin/env python3
import paho.mqtt.publish as publish

topic1 = "testtopic/topic1"
topic2 = "testtopic/topic2"

val1 = b'54.8'
val2 = b'598.45'
val3 = b'4813.9'

payload1=json.dumps({"value1":val1, "value2":val2})
payload2=json.dumps({"value3":val3)

msgs = [(topic1, payload1),
        (topic2, payload2)]

publish.multiple(msgs, hostname="localhost")

對於 on_message 函數中的訂閱者...

def on_message(client, userdata, message):
    msg = json.loads(message.payload.decode())
    res=json.loads(str(msg))
    if message.topic == topic1:
           print(str(res["value1"])+" & "+str(res["value2"]))
    else:
           print(str(res["value2"]))