Store app.post nodejs request data

Question

Speak people, I would like to know how I can use the data received from the page to use outside the app.?

var SerialPort = require('serialport');
var Readline = SerialPort.parsers.Readline;
var methodOverride = require('method-override');


//faz requerimento dos modulos
var serveStatic = require('serve-static');
const express = require('express');
const socketIo = require('socket.io');
const http = require('http');
var path = require('path');

//cria servidor
const app = express();
const server = http.createServer(app);
const io = socketIo.listen(server);

//starta servidor na porta 3000
server.listen(3000, () => {
	console.log('Servidor Online na porta 3000');
});

//define um diretorio commo public para acesso as propriedades
app.use(serveStatic(path.join(__dirname, 'public'), {
	maxAge: '1d'
	}));

// retorna index quano recebe requição
app.get('/', (req, res, next) => {
	res.sendFile(__dirname + '/index.html');
	app.use(serveStatic(path.join(__dirname, 'public'), {
		maxAge: '1d'
		}));
});

var bodyParser = require('body-parser');
var urlencodedParser = bodyParser.urlencoded({ extended: true });
app.route('/signup');
app.post( '/signup', urlencodedParser, function(req, res) {
	var portCOM = req.body.portCOM;
	var bauRATE = req.body.bauRATE;
	res.json(
		{ 
		   	message: 'signup success',
			portCOM : portCOM,
			bauRATE : bauRATE,
		}
	);
});

app.get(function(req,res){
	res.json({message: 'get request from signup'});
});

// configurações da comunicação serial
port = new SerialPort(portCOM, {
	baudRate: 9600,
    dataBits: 8,
    paridade: 'nenhum' ,
    stopBits: 1,
    flowControl: false ,
    parser: new SerialPort.parsers.Readline('\r') 	
});

//define um limite para acionar um evento
const ByteLength = require('@serialport/parser-byte-length');
const parser = port.pipe(new ByteLength({length: 4}));

//EXIBE OS LOG NO TERMINAL, INFORMAÇOES VINDA DO ARDUINO
port.open(function()
{
	console.log('Porta aberta');
});

var ModbusTCP = "";
parser.on('data', function (data)
{		
		ModbusTCP = data.toString();
		ModbusTCP = ModbusTCP.replace(/(\r\n|\n|\r)/gm,"");	
		var infLeng = ModbusTCP.length;		
		
		console.log('tamanho do envio:',infLeng);
		console.log('Valor Hexadeciaml: ' + ModbusTCP);
});

Answer 1

As far as I can tell, portCOM is used in SerialPort, but SerialPort is not being called through a middleware, it is directly at the root of the script, which means it will run only once when the server is started, even before the user sends the value of portCOM.

To execute SerialPort only when repurchase is sent to the route signup, you need to put or call the code within the callback function of the route:

app.post('/signup', urlencodedParser, function (req, res) {
    const portCOM = req.body.portCOM;
    const bauRATE = req.body.bauRATE;

    criarPorta(portCOM);

    res.json({
        message: 'signup success',
        portCOM: portCOM,
        bauRATE: bauRATE,
    });
});

function criarPorta(portCOM) {
    port = new SerialPort(portCOM, {
        baudRate: 9600,
        dataBits: 8,
        paridade: 'nenhum',
        stopBits: 1,
        flowControl: false,
        parser: new SerialPort.parsers.Readline('\r')
    });

    // .
    // .
    // .
    // Restante do código
}

Or else use the code as middleware:

app.post('/signup', urlencodedParser, criarPorta, function (req, res) {
    const portCOM = req.body.portCOM;
    const bauRATE = req.body.bauRATE;

    res.json({
        message: 'signup success',
        portCOM: portCOM,
        bauRATE: bauRATE,
    });
});

function criarPorta(req, res, next) {
    const portCOM = req.body.portCOM;

    port = new SerialPort(portCOM, {
        baudRate: 9600,
        dataBits: 8,
        paridade: 'nenhum',
        stopBits: 1,
        flowControl: false,
        parser: new SerialPort.parsers.Readline('\r')
    });

    // .
    // .
    // .
    // Restante do código

    next();
}