Router.use() requires middleware function but got an Object

Question

I was experimenting with Express 4's new Router and was wondering how one would go about doing below...

I made a file named app.js under a routes folder containing, basically, this:

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

module.exports = (function() {

    router.get('/testindex', function(req, res) {
        res.render('testindex');
    })

    return router;

})();

In my server.js file this works as expected...

var appRouter = require('./routes/app');
var apiRouter = require('./routes/api/v1.js');
app.use('/', appRouter);
app.use('/api/v1',apiRouter);

I was hoping to do something like this, but I got the error I mentioned in the title...

var router = {
    api: {
        v1: require('./routes/api/v1'),
        v2: (...)
    },
    app: require('./routes/app')
};

app.use('/api/v1', router.api.v1);
app.use('/api/v2', router.api.v2);
app.use('/', router.app);

What am I not understanding?

Answer 1

When trying to reproduce your issue, there is no problem when I remove this statement:

app.use('/api/v2', router.api.v2);

So, there is probably something wrong with the way you defined the v2 property (which you did not flesh out in your question).