Promisified Proxy-based MongoDB wrapper

db.js

var q = require('q');
var MongoClient = require('mongodb').MongoClient;


const dbUrl = require('./config').mongoUrl;

var dbConnection;

function getDb() {
    if (dbConnection) return q(dbConnection);
    dbConnection = q.nfcall(MongoClient.connect, dbUrl).then(function (db) {
        return dbConnection = db;
    });
    return dbConnection;
}

//q.longStackSupport = true;


function CollectionHandler(cname) {
    return {
        get: function (target, name) {
            return function () {
                //console.log("collection", cname, "func ", name);
                var args = arguments;
                return getDb()
                    .then(function (xdb) {
                        var c = xdb.collection(cname);
                        if (!c[name]) throw new Error("No collection's method: "+name);
                        return q.npost(c, name, args).then(function (result) {
                            if (result && result.constructor.name == 'Cursor') {
                                var h = {
                                    get: function (target, name) {
                                        if (name == 'promiseDispatch' || name == 'then') return undefined;
                                        if (Object.prototype.hasOwnProperty.call(result, name)) {
                                            //console.log("making promise for ", name)
                                            return q.npost.bind(null, result, name);
                                        } else {
                                            //console.log(result);
                                            throw "Undefined Cursor's function: " + name;
                                        }
                                    }
                                };
                                return q(Proxy.create(h, result));
                            } else
                                return result;
                        });
                    });
            }
        }
    }
}

var dbHandler = {
    get: function (target, name) {
        if (name=='ObjectID') return require('mongodb').ObjectID;
        return Proxy.create(CollectionHandler(name));
    }
};

var db = Proxy.create(dbHandler);

module.exports = db;