var express = require('express');
var app = express();

.......

app.use(express.json());
app.use(express.urlencoded());  // THIS SHOULD WORK!

......

sensorRoute.post('/', (req, res, next) => {

console.log(req.body);
const temperature = req.body.temperature;
console.log(temperature);

if (!temperature) {
    return res.status(400).send({'res': 'Missing data'});
} else {
    return res.status(200).send({'res': 'OK'});
}