data.js

var MongoClient = require('mongodb').MongoClient,
    runStartup = require("./startup.js"),
    settings = require('./config.js'),
    Guid = require('Guid');

var fullMongoUrl = settings.mongoConfig.serverUrl + settings.mongoConfig.database;
var exports = module.exports = {};

runStartup().then(function(allMovies) {
    console.log("After the setup has been complete, we have the following movies:");
    console.log(allMovies);
});

MongoClient.connect(fullMongoUrl)
    .then(function(db) {
        var movieCollection = db.collection("movies");

        // Our easiest to follow function!
        exports.getAllMovies = function() {

            // collection.find() returns a cursor, a special mongoDB object that acts as an interface to the 
            // results; 

            // If we call find() without an argument, it will return a cursor to the entire collection
            // It may paginate!

            // by calling .toArray() on the find cursor, it converts it to the promise that resolves
            // an array of all the results
            return movieCollection.find().toArray();
        };

        // we can still update our data module by adding properties here, even though it's inside a callback!
        exports.getMovie = function(id) {
            if (!id) return Promise.reject("You must provide an ID");

            // by calling .toArray() on the function, we convert the Mongo Cursor to a promise where you can 
            // easily iterate like a normal array
            return movieCollection.find({ _id: id }).limit(1).toArray().then(function(listOfMovies) {
                if (listOfMovies.length === 0) throw "Could not find movie with id of " + id;

                return listOfMovies[0];
            });
        };

        // creating data in MongoDB is very easy, as we can just use a simple insert method
        exports.createMovie = function(title, rating) {
            if (!title) return Promise.reject("You must provide a title");
            if (rating == null || rating === undefined || rating < 0 || rating > 5) return Promise.reject("You have provided an invalid rating");

            // Our insertOne method takes a JSON object as its first parameter; 
            // there are overloads that have more parameters
            // You'll notice we name our "id" as "_id"; MongoDB has a few quirks.
            // One is that it will index all documents on the _id field, 
            // Which must be a unique identifier.
            // Curiously, it doesn't let you rename it to something more sane.
            // Like 'id'.
            // Because, you know, reasons.
            return movieCollection.insertOne({ _id: Guid.create().toString(), title: title, rating: rating }).then(function(newDoc) {
                return newDoc.insertedId;
            }).then(function(newId) {
                return exports.getMovie(newId);
            });
        }

        // This is just a preview!
        // We can find on a few limited operations
        exports.getPopularMovies = function() {
            // a preview of advanced querying!
            return movieCollection.find({ rating: { $gte: 3 } }).toArray();
        };

        exports.updateMovie = function(id, newTitle, newRating) {
            if (!id) return Promise.reject("You must provide an ID");
            if (!newTitle) return Promise.reject("You must provide a title");
            if (newRating == null || newRating === undefined || newRating < 0 || newRating > 5) return Promise.reject("You have provided an invalid rating");

            // our first parameters is a way of describing the document to update;
            // our second will be a replacement version of the document;
            // next week we will learn how to use mongo atomic updates
            return movieCollection.updateOne({ _id: id }, { title: newTitle, rating: newRating }).then(function() {
                return exports.getMovie(id);
            });
        };

        exports.deleteMovie = function(id) {
            if (!id) return Promise.reject("You must provide an ID");

            return movieCollection.deleteOne({ _id: id }).then(function(deletionInfo) {
                if (deletionInfo.deletedCount === 0) throw "Could not find the document with this id to delete";

                return true;
            });
        }
    });