Express and Vue. With axios, req.body is not working - node.js

Question

Like i said in title. req.body don't work. I saw some examples and that use req.body(body-parser) well. But in my code, req.body is keep undefined. Also i found same problems and they said "app.use(bodyParser.json())" will work. But for me, no. So i ask how can i solve this error. Plz, help me.
This code is simple, Express and Vue login, signin test project. I think problem is in server file.
Server
var express = require("express");
var bodyParser = require("body-parser");
var path = require("path");
const mongoose = require("mongoose");
var index = require("./routes/index.js");
var login = require("./routes/login.js");
var signin = require("./routes/signin.js");
var app = express();
var http = require("http").Server(app);
mongoose.connect("mongodb://localhost:27017/test");
app.use('/', index);
app.use('/api/login', login);
app.use('/api/signin', signin);
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.set("port", process.env.PORT || 3000);
app.use(express.static(path.join(__dirname, 'public')));
http.listen(app.get("port"), function() {
console.log("server start in " + app.get("port"));
})
Router
const express = require("express");
const router = express.Router();
const User = require("../models/user.js");
router.post("/", function(req, res, next) {
const id = req.body.id;
const password = req.body.password;
let info = {
error: "false",
words: "",
id: "",
password: ""
}
User.findOne({ id: id }, function(err, user) {
if(err) {
info.error = "true";
info.words = "Unknown Error Come Out.";
return res.send(info);
}
if(!user) {
info.error = "true";
info.words = "Please Check Your ID or Password";
return res.send(info);
}
info.id = id;
info.password = password;
console.log(info);
return res.send(info);
})
});
module.exports = router;

Answer 1

This body can not be resolved because of your middleware declaration order. You can check from the following blog about middleware execution sequence. Basically it equals to middleware declaration order.
https://derickbailey.com/2016/05/09/in-what-order-does-my-express-js-middleware-execute/
Declare bodyParser middleware before router middleware can solve your problem
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use('/api/login', login);