var MongoClient = require('mongodb').MongoClient // move connecting into a function to avoid the 'pyramid of doom' function getConnection(cb) { MongoClient.connect('mongodb://localhost', function(err, db) { if (err) return cb(err); var simpleUser = db.collection('simple'); // to search by name, index is need to get speed // ref: http://docs.mongodb.org/manual/core/indexes-introduction/ simpleUser.ensureIndex({name: true}, function(err) { if (err) return cb(err); cb(null, simpleUser); }); }); } // an upsert will create a new record OR update an existing record // which makes things easier, in mongo, we can do this with a // findAndModify and passing the upsert option to have the update // document returned, we pass the new option as well function upsertUser(collection, name, role, cb) { collection.findAndModify({name: name}, {}, {$set: {role: role}}, {upsert: true, new: true}, cb); } // instead of finding just one user, we can list all of the documents // by passing an empty selector. This returns a 'cursor', which allows // us to walk through the documents look at how we do this in process function readAll(collection, cb) { collection.find({}, cb); } function readRole(collection, name, cb) { collection.findOne({name: name}, cb); } function printUser(user) { // make sure that we found our user if (!user) { console.log("Couldn't find the user you asked for!") } console.log(user.name + ' has the role of ' + user.role); } // the each method allows us to walk through the result set, notice // the callback, as every time the callback is called, there is // another chance of an error function printUsers(users, cb) { users.each(function(err, user) { if (err) return cb(err); printUser(user); }); } function simpleCli(operation, name, role, cb) { getConnection(function(err, collection) { if (err) return cb(err); // we need to make sure to close the database, otherwise // the process won't stop function processUser(err, user) { if (err) return cb(user); printUser(user); collection.db.close(); cb(); } // use this function when dealing with lots of users function processUsers(err, users) { if (err) return cb(err); // the callback to each is called for every result // once it returns a null, we know the result is done users.each(function(err, user) { if (err) return cb(err); if (user) { printUser(user); } else { collection.db.close(); cb(); } }); } if (operation === 'list') { readAll(collection, processUsers); } else if (operation === 'update') { upsertUser(collection, name, role, processUser); } else if (operation === 'read') { readRole(collection, name, processUser); } else { return cb(new Error('unknown operation!')); } }); } var operation = process.argv[2]; var name = process.argv[3]; var role = process.argv[4]; simpleCli(operation, name, role, function(err) { if (err) { console.log("Had an error!", err); process.exit(1); } });