Express call GET method within route from another route [duplicate]

Question

I have multiple routes. How can I get the data from the user's route (GET method), by calling it within the GET method of the group's route? What is the best way of doing this?

My app.js looks like this:

var express = require('express');

var routes = require('./routes/index');
var users = require('./routes/users');
var groups = require('./routes/groups');

var app = express();

app.use('/', routes);
app.use('/users', users);
app.use('/groups', groups);

module.exports = app;
app.listen(3000);

Then I have another file routes/users.js:

var express = require('express');
var router = express.Router();

/* GET users listing. */
router.get('/', function(req, res, next) {
  res.send('GET ON THE users!');
});

module.exports = router;

And another route routes/groups.js:

var express = require('express');
var router = express.Router();
var otherRouter = require('./users')

/* GET groups listing. */
router.get('/', function(req, res, next) {

    // call the get on users and retrieve all data from that request

    res.send('GET for the groups');
});

module.exports = router;

Answer 1

You shouldn't use routing for that. Just call the function responsible for retrieving the users from the GET groups route and do what you need with that data. The way you propose is much more expensive because you will have to make a http call.

For simplicity I'm assuming that your logic is synchronous and data stored in data/users.js:

var data = [{id:1, name: "one"},{id: 2, name: "two"}];
module.exports = function(){
  return data;
};

in routes/users.js:

var express = require('express');
var router = express.Router();
var getUsers = required('./../data/users');

router.get('/', function(req, res, next) {
  res.send(getUsers());
});

in routes/groups.js:

var express = require('express');
var router = express.Router();
var otherRouter = require('./users')
var getUsers = require('./.../data/users');

router.get('/', function(req, res, next) {
  var users = getUsers();
  //do some logic to get groups based on users variable value
  res.send('GET for the groups');
});

Answer 2

I consider what was being explained "forwarding", and it's quite useful, and available in other frameworks, in other languages.

Additionally, as a "forward" it does not have any overhead from a subsequent HTTP response.

In the case of Express, the following is available in version 4.X. Possibly other versions, but I have not checked.

var app = express()

function myRoute(req, res, next) {
  return res.send('ok')
}

function home(req, res, next) {
   req.url = '/some/other/path'

   // below is the code to handle the "forward".
   // if we want to change the method: req.method = 'POST'        
   return app._router.handle(req, res, next)
}

app.get('/some/other/path', myRoute)
app.get('/', home)