python - 分配变量并在所有值分配后发送到数据库python

Question

这是我的第一个Python脚本。我正在尝试从 Arduino 获取数据，在 Raspberry Pi 上读取数据并将其保存到数据库中。代码单独工作(我可以正确分配变量并将数据发送到数据库，但似乎无法让它们都工作。我不确定我的逻辑是否有效(将变量设置为 null，然后在它们都具有后保存)值)。感谢您的输入。

    import re
    import serial
    import MySQLdb
    import time

db =MySQLdb.connect(host = "localhost",user = "root",passwd = "example", db = "arduino")
ser =serial.Serial('/dev/ttyACM0',9600) 

humidityPattern = "Humidity\:(\d\d\.\d\d)"
tempDhPattern = "TemperatureDH\:(\d\d\.\d\d)"
barometerPattern = "PressureBMP\:(\d\d\.\d\d)"
tempBmpPattern = "TemperatureBMP\:(\d\d\.\d\d)"
tempTmpPattern = "TemperatureTMP\:(\d\d\.\d\d)"
blLightPattern = "BLLight\:(\d+)"
brLightPattern = "BRLight\:(\d+)"
frLightPattern = "FRLight\:(\d+)"
flLightPattern = "FLLight\:(\d+)"


while 1:
    line = ser.readline()
    humidity = None
    tempDh = None
    pressure = None
    tempBmp = None
    tempTmp = None
    blLight = None
    brLight = None
    frLight = None
    flLight = None

    #Humidity Sensor
    m = re.match(humidityPattern, line)
    if m is not None:      
        humidity = m.group(1)
        print "Humidity is "+humidity

    m = re.match(tempDhPattern, line)
    if m is not None:
        tempDh= m.group(1)
        print "Humidity Temp is "+tempDh

    #Pressure Sensor
    m = re.match(barometerPattern, line)
    if m is not None:
        pressure = m.group(1)
        print "Pressure is "+tempDh

    m = re.match(tempBmpPattern, line)
    if m is not None:
        tempBmp= m.group(1)
        print "Pressure Temp is "+tempBmp

    #Temp Sensor
    m = re.match(tempTmpPattern, line)
    if m is not None:
        tempTmp= m.group(1)
        print "Temp is "+tempTmp

    #Light Sensors
    m = re.match(blLightPattern, line)
    if m is not None:
        blLight= m.group(1)
        print "BL Light is "+ blLight

    m = re.match(brLightPattern, line)
    if m is not None:
        brLight= m.group(1)
        print "BR Light is "+ brLight

    m = re.match(frLightPattern, line)
    if m is not None:
        frLight = m.group(1)
        print "FR Light is "+ frLight

    m = re.match(flLightPattern, line)
    if m is not None:
        flLight = m.group(1)
        print "FL Light is "+ flLight

    if humidity and tempDh and pressure and tempBmp and tempTmp and blLight and brLight and frLight and flLight is not None:
        with db:
            cur = db.cursor()
            cur.execute('insert into weather(humidity, temp_dh, pressure,temp_bmp, temp_tmp, bl_light, br_light, fr_light, fl_light) values("%s", "%s", "%s", "%s", "%s", "%s", "%s", "%s", "%s")'%(humidity, tempDh, pressure, tempBmp, tempTmp, blLight, brLight, frLight, flLight ))
            time.sleep(5)
            print 'upload'

Answer 1

测试中存在一个问题:

if humidity and tempDh and pressure and tempBmp and tempTmp and blLight and brLight and frLight and flLight is not None:

仅测试最后一个变量 flLight 的 None。然而，如果看起来所有其他都是 None 或非空字符串，那么这个应该会意外地工作，因为 None 是假的并且每个非空字符串都是真实的。

因此，一个更大的问题是，每次循环时，您都会丢弃以前读取过的所有值，无论您是否保存了它们。

要解决这个问题，请添加一个 bool 标志 must_init 并将逻辑更改为在循环开始时类似的内容:

must_init = True而真实: 行 = ser.readline() 如果必须_init: 湿度 = 无 温度Dh = 无 压力=无 tempBmp = 无 临时温度 = 无 blLight = 无 br光=无 frLight = 无 flLight = 无 必须初始化=假

并且仅在现在最终的print 'upload'之后的with语句的最后再次设置must_init = True。

这样，您将仅在(A)第一次或(B)将之前的值保存到数据库后立即将所有变量清空，这似乎是更正确的逻辑。

其他简化改进也是可能的(例如，将变量保留为字典中的项目，这样您就不必在 any 检查中枚举它们；将 RE 表达式也放在由与您在变量字典中使用的名称相同，以极大地压缩和简化您的代码)但关键点是，按照我之前的建议添加 must_init bool 标志的代码应该工作 -- 之后你可以改进它!-)