Use node js domains in handler function

Question

I have https server written in express js. And I added domains to my server. App.js file:

var d = require('domain').create();

d.on('error', function(error) {
    console.error("Domain caught error: "+ error.stack);
});


d.run(function() {
    var express = require('express');
    var appServer = express();
    var https = require('https').createServer(options, appServer);

    https.listen(8000, function() {
        log.info('Server is listening on port ' + 8000);
    });

    appServer.use(appServer.router);
    var routes = require('./routes')(appServer); //my routes file
});

I have route handler functions in other files. How can I use domain created in my app.js file in my route files without exporting it from app.js file.

Update:

routes.js file:

var auth = require('./auth');

module.exports = function(app) {
    app.namespace('/login', function(){
    app.post('/user', auth.verifyUser);
    });
};

auth.js file:

exports.verifyUser = function(req,res) {
    //here I want to see my domain
};

Answer 1

You can pass it when you require your routes:

var routes = require('./routes')(appServer, d);

Then within your routes/index.js file:

module.exports = function(app, domain) {

    // ...

};

Update

To update the answer based on the question update, here's a possible solution to include the domain within each route definition. There are a couple ways to do this (you could make each route a class, which would be instantiated and passed the domain, then have a function defined per route, for example). Because the intent is to keep these route definition signatures function(req, res) as you've defined above for verifyUser, we're going to need to pass the domain to this route prior to calling the function. Keeping this very simple, we can do just that with a setDomain function:

Same code in your main index.js when you require your routes:

var routes = require('./routes')(appServer, d);

In your routes.js, you can pass the domain to the routes via the setDomain function:

var auth = require('./auth');

module.exports = function(app, domain) {
    auth.setDomain(domain);
    app.namespace('/login', function() {
        app.post('/user', auth.verifyUser);
    });
};

Finally, in your auth.js file, you can get the domain, and have access to it within the scope of the file to use it in the verifyUser function:

var myDomain;

module.exports.setDomain = function(domain) {
    myDomain = domain;
};

module.exports.verifyUser = function(req, res) {
    res.send("myDomain: " + myDomain);
};

I'm not sure I really like this solution, but again, it's keeping the signature the same for verifyUser. Maybe you'll think of a better one, or want to refactor your code to better make use of this domain you're passing around within your code (maybe define it somewhere else and pull it from there wherever it's needed).