Question

我是python的新手，仍然在学习，所以请对我保持温柔。我已经获得了订阅MQTT主题并接收代码的python脚本。

如果有效载荷等于该代码，则它将设置计时器，该计时器将打开显示屏。时间过后，显示器将关闭，直到有效载荷再次等于之前所述的相同代码为止。

这是我的代码：

 startTipLabel.text = "longer text what you want"
 startTipLabel.numberOfLines = 0
 startTipLabel.lineBreakMode = NSLineBreakMode.ByWordWrapping

问题：

运行代码时，出现错误消息：

    import paho.mqtt.client as mqttClient
    import time
    from subprocess import call
    from time import sleep


    def on_connect(client, userdata, flags, rc):
    #    print("Connected with result code "+str(rc))
        client.subscribe("home/OpenMQTTGateway/433toMQTT")
    #def on_message(client, userdata, msg):
    #    if msg.topic == 'home/OpenMQTTGateway/433toMQTT':
    #        print(str(msg.payload))


def on_message(client, userdata, msg):
    global myGlobalMessagePayload
    if msg.topic == 'home/OpenMQTTGateway/433toMQTT':
        myGlobalMessagePayload = msg.payload

    timeUntilDisplayOff = 240

    timer = timeUntilDisplayOff

    while True:

        if msg.payload == '1381683':
                timer = timeUntilDisplayOff
                print ("Motion detected! Setting timer to " + str(timer) + " seconds.")


            if timer > 0:
                    if timer % 10 == 0:
                            print ("Timer: " + str(timer) + " seconds")
                    timer -= 1

            elif timer == 0:
                    call(['vcgencmd', 'display_power', '0'])

                    print ("Timer is 0. Display turned off. Waiting for motion...")
                    # display is now off. we wait for motion and turn it on
                    myGlobalMessagePayload == '1381683'
                    call(['vcgencmd', 'display_power', '1'])
                    timer = timeUntilDisplayOff

            sleep(1)

我还使用通用代码重复了该过程，即在Traceback (most recent call last): File "test2.py", line 26, in <module> if msg.payload == '1381683': NameError: name 'msg' is not defined之后接近尾声，它看起来正确吗？还是可以做得更好？

谢谢

更新：

因此，我感谢@blt对我的代码进行了排序。但是，当msg.payload匹配“ 1381683”时，我的代码将继续循环播放。我得到以下信息：

# display is now off. we wait for motion and turn it on

以上内容不断循环播放...

Answer 1

缩进在python中很重要。

您需要将以下代码块缩进一级：

timeUntilDisplayOff = 1800

timer = timeUntilDisplayOff

while True:

否则，本节后面的代码将在范围内没有msg变量（因此会出现错误）。

所以on_message函数的前半部分是：

def on_message(client, userdata, msg):
    global myGlobalMessagePayload
    if msg.topic == 'home/OpenMQTTGateway/433toMQTT':
        myGlobalMessagePayload = msg.payload

    timeUntilDisplayOff = 1800

    timer = timeUntilDisplayOff

    while True:

        if msg.payload == '1381683':
                timer = timeUntilDisplayOff
                print ("Motion detected! Setting timer to " + str(timer) + " seconds.")

时间从mqtt有效负载打开/关闭屏幕

1 个答案: