Python：全局变量未通过函数获取 affected/changed

Question

我正在处理的 Flask 应用程序出现问题。

名为 buttonNum 的全局变量应该随着每次调用 button() 而改变；但是，ardCom() 中的 buttonNum 不受影响，不承认使用 button() 对其所做的更改。我在网上找到了有关如何使用全局变量的示例，据我所知，这应该可行。

感谢所有帮助。谢谢

import time
import json
import serial
import flask
from multiprocessing import Process
from flask import Flask, request, render_template, make_response

buttonNum = 0
app = Flask(__name__)

@app.route('/')
def default():
    headers = {'Content-Type': 'text/html'}
    return make_response(render_template('index.html'),200,headers)

@app.route('/setup', methods=['POST'])
def setup():
    data = request.get_json
    return {'result' : "Success"}

@app.route('/button', methods=['POST'])
def button():
    global buttonNum
    buttonNum= int(request.form['number'])
    typeOf = int(request.form['type'])
    value = int(request.form['value'])
    return "success"

def ardCom():
    global buttonNum
    county = 1
    ph = b''
    ph = ser.read()

    if ph == b'S':
        ser.write(ph)
        while (ph != b'E'):
            ph = ser.read()
            if ph == b'E':
                ser.write(ph)
                break
            #print(str(buttonNum))
            if ph == b'\x00' and buttonNum != county:
                writeOut(b'\x00')
                county += 1
            if ph  == b'\x01' or buttonNum == county:
                writeOut(b'\x01')
                print("Button", end = " ")
                print(county, end = " ")
                print("has been pressed.")
                county += 1

def writeOut(datByte):
    ser.write(datByte)

def runApi():
    app.run(host='0.0.0.0')

if __name__  == '__main__':
    ser = serial.Serial('/dev/ttyACM0', 9600, timeout=1)
    ser.flush()
    time.sleep(1)
    apiProcess = Process(target=runApi)
    apiProcess.start()
    while True:
        ardCom()

Answer 1

当 flask 服务器运行时，它可能会运行一些实例。为了使您的代码有效，您可以将值存储在文件中（如 json）或数据库中。

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