Pass array to routes/index.js from app.js in Nodejs with Express 4

Question

How can I pass an array of objects to the routes middle-ware so that I can render the view depending on the variables passed.

Currently, this is the layout I am working with

app.js

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

ARRAY = [objects];
app.use('/', index);

routes/index.js

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

router.get('/', function(req, res, next){
  res.render('index', {data: ARRAY});
});

module.exports = router;

index.jade

extends layout
block content
  each d in data
    div!= d.method()

Currently the only solution I can produce that actually works is to use global variables, but this is not sustainable or scalable. I have tried app.set('shrinkr', shrinkr); and app.locals but cannot get either of these to work with the layout of my app. From my understanding of the Express4 framework I should be able to do something like this in app.js:

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

but I cannot get the implementation correct, and there is no info about this on the web.

Ethan Brown · Accepted Answer · 2016-05-02 19:40:31Z

2

There are multiple ways that you can tackle this, but if you want to "bake" the array into the middleware (as your code sample suggested), you can do this:

var express = require('express');

module.exports = function(array) {
    var router = express.Router();
    return router.get('/', function(req, res, next){
      res.render('index', {data: array});
    });
}

Then you can use it as you suggested:

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

Because new middleware is created every time you invoke the exported function, you can bake independent arrays into different middleware:

var index1 = require('./routes/index')(["array 1"]);
var index2 = require('./routes/index')(["array 2"]);

Which may or may not be useful to you, depending on your needs.

edited May 2, 2016 at 19:40

answered May 2, 2016 at 4:15

Ethan Brown

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5 Comments

William Paul Over a year ago

Thank you for your answer - this looks exactly what I need however when I try to implement it with app.use('/', index); I get thrown a 'Router.use() requires middleware function but got a ' + gettype(fn) -- how can I use this implementation with app.use

Ethan Brown Over a year ago

Sorry, I forgot a return statement; it's been updated, and it should work now.

William Paul Over a year ago

Okay cheers, that seems to function as expected. Problem I am having now is related to the fact that new middleware is created every time an exported function is invoked. How can I do app.use with a defined route with a consistently changing array? I have a loop which updates an array every 10 seconds, and I want the middleware to update with it, but redefining index in the same loop that updates the array like loop{ array1.push(1); index = require('./routes/index')(array1);} doesn't work.. :(

Ethan Brown Over a year ago

Hi, William, it works for me. I tried it out with this program: gist.github.com/EthanRBrown/824a776c3405901c47fe427e8c3d9338

William Paul Over a year ago

Okay thanks for your help Ethan. I wrote a similar debug app and it worked, must be a problem with how my app is structured. Cheers

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