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node.js/express.js connection pool Cannot read properties of undefined (reading 'getConnection')

So I created a new node.js project and used express.js to build the basics to start of. Now I want to do a simple get call to get data from my database through a connection pool. When I do the call in app.js there is no problem, but when trying to do the same call from my users.js file in a get route it throws 'connection pool Cannot read properties of undefined (reading 'getConnection')'.
app.js
var createError = require('http-errors');
var express = require('express');
var path = require('path');
var cookieParser = require('cookie-parser');
var logger = require('morgan');
var mysql = require('mysql');
var indexRouter = require('./routes/index');
var usersRouter = require('./routes/users');
var app = express();
// establish connection to database
var conpool = mysql.createPool({
connectionLimit: 10,
host: 'localhost',
user: '****',
password: '****',
database: 'db_name'
});
// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');
app.use(logger('dev'));
app.use(express.json());
app.use(express.urlencoded({ extended: false }));
app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));
app.use('/', indexRouter);
app.use('/users', usersRouter);
// catch 404 and forward to error handler
app.use(function(req, res, next) {
next(createError(404));
});
// error handler
app.use(function(err, req, res, next) {
// set locals, only providing error in development
res.locals.message = err.message;
res.locals.error = req.app.get('env') === 'development' ? err : {};
// render the error page
res.status(err.status || 500);
res.render('error');
});
module.exports = {app, conpool};
user.js (located in routes directory which is on the same hierarchy level as app.js)
var express = require('express');
var router = express.Router();
var db = require('../app').conpool;
/* GET users listing. */
router.get('/get', function (req, res, next) {
db.getConnection((err, connection) => {
if (err) throw err;
var sql = null;
if (req.query.name) {
sql = 'SELECT * FROM users WHERE name = ' + sql.escape(req.query.name);
} else {
sql = 'SELECT * FROM users';
}
connection.query(sql, function (err, result) {
if (err) throw err;
console.log(result);
});
});
});
module.exports = router;
Does anyone have any idea why this is happening? Is there something wrong with how I am using module.exports? Is it a problem of trying to call a function on a reference instead of the original pool object?

It seems Evert's solution was the one I was looking for. I'll describe the changes I made compared to the files shown in my question to show how it solved it.
I made a completely new file database.js (on the same level of hierarchy as app.js):
var mysql = require('mysql');
var conpool = mysql.createPool({
connectionLimit: 10,
host: 'localhost',
user: '****',
password: '****',
database: 'db_name'
});
module.exports = conpool;
and deleted all these lines of code from app.js
in user.js only one line changed:
var db = require('../app.js')
to
var db = require('../database');

Using variables through scripts using module.exports not working

So im pulling my hair here and everything I've tried hasn't worked. I have a simple node.js app structure, like this:
var express = require('express');
var path = require('path');
var mysql = require('mysql');
var indexRouter = require('./routes/index');
var usersRouter = require('./routes/users');
var app = express();
app.use(express.json());
app.use(express.urlencoded({ extended: false }));
app.use(express.static(path.join(__dirname, 'public')));
app.use('/', indexRouter);
app.use('/users', usersRouter);
//Database handler
//Here is completed with the data
var con = mysql.createConnection({
host: "",
user: "",
password: "",
database: ""
});
con.connect(function (err) {
if(err) throw err;
console.log("connected");
});
app.listen(55132, function () {
console.log("Server running at port 55132");
});
module.exports = app;
Quite simple, some routing but nothing weird. I need to use the variable con in my other scripts, so i've tried this:
module.exports.database = con;
So i should be able to use it in my index.js script (see var indexRouter), soooo here is the index.js script:
var express = require('express');
var router = express.Router();
let app = require('../app');
let connection = app.database;
console.log(app); //Here returns {} so I can´t access any of the properties of the module
/* GET home page. */
router.get('/', function(req, res, next) {
}
module.exports = router;
I don't know what should I do, some suggestion?

for forther reading i recommend you to read this
https://nodejs.org/api/modules.html#modules_exports_shortcut
just change you app file export to
module.exports = {app,con};
and in your index file
const {app,con} = require('./app');
let connection = con;

You can you try with
for and example :
var function = function(coid, userid, callback) {}
exports.function = function ;
in your case
exports.database = con;
Now it should work, you won't need to add module in the above.

issue with angular 4 and nodejs , serve index.html based on URL like /admin and /

Hi i have setup three project api(nodejs) , admin(angular 4) and website(angular 4) , after build i got two UI folder admin-dist and web-dist , I want to access these app based on URL '/admin' will access admin-dist and '/' will access web-dist , I have placed these two folder on of api folder
For accessing these app i have written node code like this ,But i am not able to access ,
Please help me, Thanks in advance ..
app.js
var express = require('express');
router = express.Router();
var port = process.env.PORT || 3000;
var bodyParser = require('body-parser');
var mongoose = require('mongoose');
var cookieParser = require('cookie-parser');
var fs = require('fs')
var morgan = require('morgan')
var path = require('path')
var cors = require('cors');
var User = require('./models/user.model');
var dbConfig = require('./config/db');
var app = express();
app.use(cors());
app.use(cookieParser());
// create a write stream (in append mode)
var accessLogStream = fs.createWriteStream(path.join(__dirname, 'access.log'), {flags: 'a'});
// setup the logger
app.use(morgan('combined', {stream: accessLogStream}));
mongoose.Promise = global.Promise;
mongoose.connect(dbConfig.db, function (err) {
if (err) {
console.log('faild to connect with mongo DB', err);
}
else {
console.log('Connection open with mongo db');
}
})
app.use(bodyParser.urlencoded({extended: true}));
app.use(bodyParser.json());
app.use('/api', router);
var userRoute = require('./routes/user.route')(router);
// var profileRoute = require('./routes/profile.route')(app);
// var productRoute=require('./routes/products.route')(app);
app.use(express.static(__dirname + '/admin-dist'));
app.get('/admin', function (req, res) {
console.log('admin route');
return res.sendFile(path.resolve('./admin-dist/index.html'));
});
app.get('/admin/*', function (req, res) {
res.sendFile(path.resolve('./admin-dist/index.html'));
});
app.use(express.static(__dirname + '/front-dist'));
app.get('/', function (req, res) {
console.log('web route');
return res.sendFile(path.resolve('./front-dist/index.html'));
});
app.use('/*',function(req, res) {
return res.sendFile(path.resolve('./front-dist/index.html'));
});
app.listen(port, function (err) {
if (err) {
console.log(err);
}
else {
console.log('Server api runing on port ', port);
}
})

Node js express js proxy

Here is an image of the error. I developed an application on AngularJS, and when I run node server by using public wifi my application is running fine. However, when I run it on org network/company wifi my application doesn't work. Any help?
server.js code
var express = require("express");
var open = require("open");
var bodyParser = require("body-parser");
var cookieParser = require("cookie-parser");
var fs = require("fs");
var path = require("path");
var auth = require("./api/auth");
//var users = require("./api/users");
var transactions = require("./api/transactions");
//var serviceTypes = require("./api/serviceTypes");
var app = express();
app.use(bodyParser.urlencoded({extended: false}))
app.use(bodyParser.json());
app.use(cookieParser());
app.use(express.static("boilerplate"));
app.use(express.static("./"));
app.listen(3000, function () {
console.log("server is running on port:3000");
open("http://localhost:3000/");
});
app.get("/", function (req, res) {
res.sendFile(path.join(__dirname, "boilerplate/index.html"));
});
app.use("/auth", auth);
//app.use("/users", users);
app.use("/transactions", transactions);
//app.use("/servicetypes", serviceTypes);

How to query using MySQL in an EJS File

I am trying to run a query in a view (.ejs file). However, since the keyword require is not defined in a .ejs file, I need to export it from my main file, server.js.
The whole code for my server.js file is below and this is the specific snippet with which I need help.
app.engine('html', require('ejs').renderFile);
exports.profile = function(req, res) {
res.render('profile', { mysql: mysql });
}
I need to be able to use the mysql.createConnection in my profile.ejs file.
Any help would be great.
// server.js
// set up ======================================================================
// get all the tools we need
var express = require('express');
var app = express();
var port = process.env.PORT || 8080;
var mongoose = require('mongoose');
var passport = require('passport');
var flash = require('connect-flash');
var morgan = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');
var session = require('express-session');
var configDB = require('./config/database.js');
var Connection = require('tedious').Connection;
var config = {
userName: 'DESKTOP-S6CM9A9\\Yash',
password: '',
server: 'DESKTOP-S6CM9A9\\SQLEXPRESS',
};
var Request = require('tedious').Request;
var TYPES = require('tedious').TYPES;
var mysql = require('mysql');
var con = mysql.createConnection({
host: "localhost",
user: "root",
password: "yashm"
});
con.connect(function(err) {
if (err) throw err;
console.log("Connected!");
var sql="Select * from test.productlist";
con.query(sql, function (err, result) {
if (err) throw err;
console.log(result);
});
});
app.engine('html', require('ejs').renderFile);
exports.profile = function(req, res) {
res.render('profile', { mysql: mysql });
}
//--------------------------------------------------------------------------------
// configuration ===============================================================
mongoose.connect(configDB.url); // connect to our database
require('./config/passport')(passport); // pass passport for configuration
// set up our express application
app.use(morgan('dev')); // log every request to the console
app.use(cookieParser()); // read cookies (needed for auth)
app.use(bodyParser()); // get information from html forms
app.set('view engine', 'ejs'); // set up ejs for templating
// required for passport
app.use(session({ secret: 'test run' })); // session secret
app.use(passport.initialize());
app.use(passport.session()); // persistent login sessions
app.use(flash()); // use connect-flash for flash messages stored in session
// routes ======================================================================
require('./app/routes.js')(app, passport); // load our routes and pass in our app and fully configured passport
// launch ======================================================================
app.listen(port);
console.log('The magic happens on port ' + port);

Like already said in the comment, you have to do your query logic in your server.js and then pass the data to your view (or maybe even pre-process it!)
exports.profile = function(req, res) {
con.query('SELECT 1', function (error, results, fields) {
if (error) throw error;
// connected!
res.render('profile', { data: results });
});
}
In your ejs you can loop trough the data, and acces the fields as data[i]['fieldname']
<ul>
<% for(var i=0; i<data.length; i++) {%>
<li><%= data[i]['id'] %></li>
<% } %>
</ul>