Pass express() app variable from one file to another

Question

Hello guys, first of all, I know here is a lot of similar posts, but unfortunately I still can't figure out my trouble.

I have a file server.js , where I declare my app variable and invoke some config stuff:

var app = express();
...

In my other file which is on path ./server/routes/PostApi.js I need to call code like this:

app.get('/api/posts', function(req, res) {
// use mongoose to get all posts in the database
Post.find(function(err, posts) {
    // if there is an error retrieving, send the error. nothing after res.send(err) will execute
    if (err) {
        res.send(err);
    }
    res.json(posts); // return all posts in JSON format
}); 
...

on the end of this file i call:

module.exports = PostApi;

which is required in server.js mentioned at first:

var PostApi = require('./server/routes/PostApi');

Please, what is best practice these days for passing app variable to my api file? Thank you!

Answer 1

So the direct answer to your question is that you can turn your route code into a function that accepts the app as a param:

module.exports = function(app){

   app.get('/api/posts', function(req, res) {
   // use mongoose to get all posts in the database
   Post.find(function(err, posts) {
       // if there is an error retrieving, send the error. nothing after       res.send(err) will execute
       if (err) {
           res.send(err);
       }
       res.json(posts); // return all posts in JSON format
   }); 
   ...
};

that said, it's also common for folks to instead build a router inside their routes and export that, for the app to then require and use:

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

    router.get(''/api/posts', function(req, res) {
           // use mongoose to get all posts in the database
       Post.find(function(err, posts) {
           // if there is an error retrieving, send the error. nothing after       res.send(err) will execute
           if (err) {
               res.send(err);
           }
           res.json(posts); // return all posts in JSON format
       });

module.exports = router;

// in app.js

...
app.use(require('./myrouter.js'));

Answer 2

The Paul´s answer is correct, but without too many changes on your files you can do this.

module.exports = function(app){

   app.get('/api/posts', function(req, res) {
   ....
   }); 
};

in app.js

var PostApi = require('./server/routes/PostApi')(app);

Answer 3

This works for me :

index.js

var express = require('express'); // include
var moduleA = require('./moduleA'); // include

var app = express();
var moduleA = new moduleA();

moduleA.execute(app);

app.listen(process.env.PORT || 8080);

moduleA.js

function moduleA() {
}

moduleA.prototype.execute = function(app) {
    // publish endpoints
    app.get('/register',
        function(req, res)
        {
            res.type('text/plain');
            res.send('Hello world express!!');
        }
    );
};


module.exports = moduleA;

And test it with:

http://localhost:8080/register