Node/Express - Route/Function conundrum - circular reference - node.js

Question

Smarter programmers, please advise:
two variables coming in from an AJAX post (username, pic)
get them at the route users.js from req.body
have my functions in a file main.Funcs exported to server.js
I can't figure out how to get the variables out of my route and into my server.js, so that I can use them with my functions. Can't figure out how to do it without circular 'require' between routes and mainFuncs.
QUESTIONS:
How do you access variables from routes without (1) making global variables, nor (2) circular require between routes and mainFuncs?
Could set global variables but bad? Some way to call them in a big function that gives access to scope without making global?
server.js
var express = require('express');
var mainFuncs = require('./mainFunctions.js');
mainFuncs.startServer();
mainFuncs.sqlConnectionCheck();
mainFuncs.learnFace(username, picLink);
mainFuncs.js
const client = some api methods, input from route --> api --> json back
var express = require('express');
var users = require('./routes/users');
var bodyParser = require('body-parser');
app.use('/users', users);
var app = express();
app.use(bodyParser.urlencoded());
app.use(bodyParser.json());
app.use(express.static('public'));
app.use('/', main);
app.use('/users', users);
app.use('/profile', profile);
var mainFuncs = {
startServer: function () {
app.listen(3000, function() {
models.users.sync({ force: true });
models.userPicData.sync({ force: true });
console.log('Listening on port 3000!');
});
},
sqlConnectionCheck: function (){
sequelize
.authenticate()
.then(function(err) {
console.log('Connection to mysql: success.');
})
.catch(function (err) {
console.log('Connection to mysql: failed with these errors: ', err);
});
},
learnFace: function (username, picPath) {
client.faces.detect({ urls: picPath, attributes: 'all' })
.then(function(result){
var newLearn = JSON.parse(result);
var newTid = newLearn.photos[0].tags[0].tid;
var fullNameSpace = username + '#notARealNameSpace';
console.log('You have been registered with the name: ' + username);
client.tags.save(newTid, fullNameSpace, {label: nameString, password: 'optionalPassword'});
client.faces.train(nameString, { namespace: 'urface' });
})
},
};
module.exports = mainFuncs;
routes/users.js
var express = require('express');
var router = express.Router();
var bodyParser = require('body-parser');
var app = express();
router.post('/create', function(req,res){
var username = req.body.username;
var picLink = req.body.pic;
});
module.exports = router;

Answer 1

Typically express apps are structured so that the Business Logic, Routes and Express server are in separate locations. The actual logic to your app goes inside a directory /lib. Your routes go inside /routes and your server.js goes into your project root.
/<root>
/lib
/public
/routes
server.js
package.json
Do you mean my mainFuncs should be imported into the router? It just seems like I'm writing most of the program in the routes at that point?
No, your logic goes into separate files inside /lib and your /routes will require it when necessary. This approach is decoupled and allows your logic to live outside of your routes. The logic may be implemented in multiple routes if necessary yet be centralized and easy to maintain. This leaves your routes free to only implement the code needed to determine the response and update session state.
The above code could be structured as so:
server.js
const express = require('express');
const bodyParser = require('body-parser');
const users = require('./routes/users');
// Place DB and any other initialization here in server.js
// so it will be guaranteed to execute prior to the server listening
const app = express();
const port = process.env.PORT || 1337;
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());
app.use(express.static('public'));
app.use('/users', users);
app.listen(port, () => {
console.log(`Listening on ${port}`);
});
module.exports = app;
/lib/learnFace.js
const client = require('<package>'); // Some package etc per your question
function learnFace(username, picPath) {
return client.faces.detect({ urls: picPath, attributes: 'all' })
.then(function(result){
let newLearn = JSON.parse(result);
let newTid = newLearn.photos[0].tags[0].tid;
let fullNameSpace = username + '#notARealNameSpace';
console.log('You have been registered with the name: ' + username);
client.tags.save(newTid, fullNameSpace, {label: nameString, password: 'optionalPassword'});
client.faces.train(nameString, { namespace: 'urface' });
});
}
module.exports = learnFace;
/routes/users.js
const router = require('express').Router();
const learnFace = require('../lib/learnFace');
router.post('/create', (req, res) => {
let username = req.body.username;
let picLink = req.body.pic;
return learnFace(username, picLink)
.then(() => {
return res.sendStatus(201);
})
.catch((err) => {
return res.sendStatus(500);
})
});
module.exports = router;
Also you don't need to require Express in every file like you are no need to, only require the things you need in files that you are using.