Syntax to export a variable using module.exports

Question

I would like to export the variable db so it would be available in app.js

app.js

'use strict';
var config = require('./config');
console.log(config);
var database = require('./services/database')(config);
database.connect(...) // database is undefined

Exception: TypeError: Cannot call method 'connect' of undefined

config.js

var config = module.exports;
config.mongodb = {
  port: process.env.MONGODB_PORT || 27017,
  host: process.env.MONGODB_HOST || 'localhost',
  db: "test"
};

services/database.js

module.exports = function(config) {
    var mongoskin = require('mongoskin');
    console.log(config);
    var dburl = config.mongodb.host + ":" + config.mongodb.port + "/" + config.mongodb.db + "?auto_reconnect";
    console.log(dburl);
    var db = mongoskin.db(dburl);
    // I want to export db
}

peter.petrov · Accepted Answer · 2014-01-04 16:31:15Z

1

I would export an object which has db property. That object may have other properties (function/data) too. This sample code exports an object with a function property fun and a data property db.

module.exports = function(param) {
  return {
    fun : function() {
       // whatever code is needed
    },
    db : {
       // whatever data is needed
    }
  };
}

edited Jan 4, 2014 at 16:31

answered Jan 4, 2014 at 16:19

peter.petrov

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1 Comment

Sydney Over a year ago

Would you mind adding sample code to achieve that? My main problem is the syntax to use

rgtk · Accepted Answer · 2014-01-04 16:22:32Z

1

Node cache modules' value so it's always will return same db instance.

services/database.js

module.exports = function(config) {
    var mongoskin = require('mongoskin');
    console.log(config);
    var dburl = config.mongodb.host + ":" + config.mongodb.port + "/" + config.mongodb.db + "?auto_reconnect";
    console.log(dburl);
    var db = mongoskin.db(dburl);

    return db;
};

Also, you don't need to database.connect in app.js, because you are already connected in services/database.js.

answered Jan 4, 2014 at 16:22

rgtk

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