python Mqtt subscribe how to delete first session/message

问题

I created a Mqtt subscribe with python that has HA as broker … when I make the first connection I start a series of messages of all the mqtt buttons that I connected even if I am not activating them because my subscription is "house/click/ # ". Once the list is done … if you press a button I start getting the messages I need … is there a way to delete this first list that it gives me.

this is the code I use:

import paho.mqtt.client as paho
import pandas as pd
import pyautogui
import os
import platform


def on_subscribe(client, userdata, mid, granted_qos):
    print("Subscribed: "+str(mid)+" "+str(granted_qos))


def on_message(client, userdata, msg):
    pyautogui.FAILSAFE=False
    os_system=platform.system()


    # Selezione area dello screenshot

    if os_system == 'Darwin':
        region=(10,80, 850, 100) #MAC
    else:
        region=(60,130,900,250) #RASP

    tab_pos=pd.read_csv('table_position.csv')
    print(msg.topic+"  "+str(msg.payload)+" "+str(msg.qos))
    mqtt_name=str(msg.topic).split("click/")[0]+str(msg.topic).split("click/")[1]
    mqtt_payload=msg.payload.decode('utf-8')
    index_loc=tab_pos.index[tab_pos['mqtt_topic'] == mqtt_name].tolist()
    x_loc=tab_pos.iloc[index_loc[0]][0]
    y_loc=tab_pos.iloc[index_loc[0]][1]
    new_xloc=x_loc+region[0]
    new_yloc=y_loc+region[1]
    if tab_pos.iloc[index_loc[0]][5] == "cover":
        if str(mqtt_payload) == "OPEN":
            if str(mqtt_payload) == "STOP":
                pyautogui.click(new_xloc+8,new_yloc+2)
                pyautogui.moveTo(region[0],region[1])
                print(str(new_xloc)+","+str(new_yloc))
            else:
                pyautogui.click(new_xloc+8,new_yloc+2)
                pyautogui.moveTo(region[0],region[1])
                print(str(new_xloc)+","+str(new_yloc))
        if str(mqtt_payload) == "CLOSE":
            if str(mqtt_payload) == "STOP":
                pyautogui.click(new_xloc+8,new_yloc+25)
                pyautogui.moveTo(region[0],region[1])
                print(str(new_xloc)+","+str(new_yloc))
            else:
                pyautogui.click(new_xloc+8,new_yloc+25)
                pyautogui.moveTo(region[0],region[1])
                print(str(new_xloc)+","+str(new_yloc))
    else:
        pyautogui.click(new_xloc+10,new_yloc+10)
        pyautogui.moveTo(region[0],region[1])
        print(str(new_xloc)+","+str(new_yloc))


client = paho.Client(client_id = "atena_mqtt_click")
client.on_subscribe = on_subscribe
client.on_message = on_message
client.username_pw_set("xxxx", "xxxxx")
client.connect("XXX.XXX.XXX.XXX", 1883)
client.subscribe("house/click/#", qos=1)
client.loop_forever()

this is the output

Subscribed: 1 (1,)
house/click/xxxxxx/light b’OFF’ 0
711,104
house/click/xxxxxx/alarm b’OFF’ 0
454,134
house/click/xxxxxx/light b’OFF’ 0
795,104
house/click/xxxxxxx/cover b’STOP’ 0

after these messages that all come together I can begin to have the messages due to my actions on the buttons

someone could tell me how I can do a clean session without having these first lines?

thanks

回答1:

Check your MQTT Publisher flag. If your publisher is using the 'retain flag' you need to make it false.

and to delete a retained message from a topic, a client must either replace it with another message with retain flag set to True OR a client must publish a blank message with retain flag set to True on that topic. This is the only way to delete a retained message.

"A retained message is a normal MQTT message with the retained flag set to true. The broker stores the last retained message and the corresponding QoS for that topic. Each client that subscribes to a topic pattern that matches the topic of the retained message receives the retained message immediately after they subscribe. The broker stores only one retained message per topic". Source: https://www.hivemq.com/blog/mqtt-essentials-part-8-retained-messages/

来源：https://stackoverflow.com/questions/63441669/python-mqtt-subscribe-how-to-delete-first-session-message