How to pass a variable through routes in Express

Question

app.js

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

var testVar = "Hello World";

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

app.use('/', index);

index.js

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

router.get('/', function(req, res) {
   console.log(testVar);
});

module.exports(router);

How to pass the variable "testVar" in ./routes/index.js? Someone has an idea? Thanks in advance!

you can make a middleware function and set a variable from there — nha, Jan 05 '16 at 09:59
Something like that : `app.all('*', function(req, res, next){ req.myvar = "this is in my request now"; next(); });` — nha, Jan 05 '16 at 10:05
See : http://stackoverflow.com/questions/18875292/passing-variables-to-the-next-middleware-using-next-in-expressjs — nha, Jan 05 '16 at 10:06

score 1 · Answer 1 · answered Jan 05 '16 at 10:09

You can do that in a middleware like this:

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

var testVar = "Hello World";

var myMiddleWare = function (req, res, next) {
    req.testVar = testVar;

    next();
}

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

app.use('/', myMiddleWare, index);

The middleware is called for every request to the index.

The only difference to a normal route-function is the third parameter "next", which might be called to go to the next step (the index), or not called (in case an error happend or something else)

You can read more about middlewares here: http://expressjs.com/en/guide/using-middleware.html

score 1 · Answer 2 · answered Jan 05 '16 at 10:11

1

You can do this in app.js:

app.use(function (req, res, next) {
    req.testVar = testVar;
    next();
});

Then in index.js just get the req variable you set before:

router.get('/', function(req, res) {
   console.log(req.testVar);
});

answered Jan 05 '16 at 10:11

michelem

14,430
5
50
66

score 0 · Answer 3 · answered Jan 05 '16 at 10:13

0

You can pass a variable like below


   app.get('/user/:testVar', function (req,res,next) {
    });

Then retrieve the parameter with

req.params.testVar

answered Jan 05 '16 at 10:13

Ktonneh

112
8

score 0 · Answer 4 · answered Jan 05 '16 at 11:12

I don't know your purpose for doing this. But this is how you can send data to ./routes/index.js without middleware and also get the router.

index.js

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

router.get('/', function(req, res) {
   console.log(testVar);
});

module.exports = function(testData){
    testVar = testData;
    return router;
}

app.js

var testVar = "Hello World";
var index = require('./routes/index')(testVar);

How to pass a variable through routes in Express

4 Answers4