W3D4

memorydb.js

const chalk = require('chalk');

const tasks = [
    { title: 'Hustle', status: 'complete' },
    { title: 'Grind', status: 'pending' },
    { title: 'Repeat', status: 'pending' },
];

const statusChalker = {
    pending: chalk.bold.red,
    complete: chalk.bold.green
}

function showTasks() {
    console.log(chalk.bold.underline( tasks.length + ' tasks'));

    tasks.forEach(function (task, index) {
        console.log(statusChalker[task.status](task.title));
    });
}

function addTask(title) {
    return tasks.push({ title: title, status: 'pending' });
}

function removeTask(index) {
    return tasks.splice(index, 1);
}

showTasks();

addTask('Do more');
showTasks();

addTask('Move fast');
addTask('Break things');
removeTask(2);
showTasks();

mongodb.js

const chalk = require('chalk');
const Mongo = require('mongodb');

const MongoClient = Mongo.MongoClient;
const MONGODB_URI = "mongodb://127.0.0.1:27017/lhl-tasks";

const statusChalker = {
    pending: chalk.bold.red,
    complete: chalk.bold.green
}

function showTasks(mongoInstance) {
    return new Promise(function (resolve, reject) {
        mongoInstance.collection("tasks").find({}).toArray(function (err, tasks) {
            if (err) {
                console.log(chalt.red(err));
                return reject(err);
            }

            console.log(tasks.length + ' tasks');

            tasks.forEach(function (task) {
                console.log(task._id + ': ' + statusChalker[task.status](task.title));
            });

            return resolve();
        });
    });
}

function addTask(mongoInstance, title) {
    return new Promise(function (resolve, reject) {
        mongoInstance.collection("tasks").insertOne({
            title: title,
            status: 'pending'
        }, function (err, result) {
            if (err) {
                console.log(chalt.red(err));
                return reject();
            }

            return resolve();
        });
    });
}

function removeTask(mongoInstance, _id) {
    return new Promise(function (resolve, reject) {
        mongoInstance.collection("tasks").deleteOne({
            _id: Mongo.ObjectID(_id)
        }, function (err, result) {
            if (err) {
                console.log(chalt.red(err));
                return reject();
            }

            return resolve();
        });
    });
}

MongoClient.connect(MONGODB_URI, (err, mongoInstance) => {
    if (err) {
        throw err;
    }

    console.log(`Connected to MongoDb: ${MONGODB_URI}`);

    showTasks(mongoInstance)
        .then(function () {
            return addTask(mongoInstance, 'Item at ' + new Date().toTimeString())
        })
        .then(function () {
            return showTasks(mongoInstance);
        })
        .then(function () {
            return removeTask(mongoInstance, '5b05c566c71b2a20785bf5ec');
        }).then(function () {
            mongoInstance.close();
            process.exit();
            return
        });
});

W3D4 outline.md

Background

1. Need for persistence
2. Persistence in the real world
3. Persistence in computers
   • In memory
   • Text/JSON/binary files
   • Databases
4. Types of databases

MongoDB

1. NoSql database
   • Server > Databases > Collections > Documents
   • Collections
     • Misconceptions
2. Interfacing with the database
   • Command line/shell
   • API/driver
3. Commands

show dbs
use <db>

# read
db.<collection>.find({"email": "[email protected]" })
db.<collection>.findOne({"profile.name": "Jack Belly" })

# write 
db.createCollection('collectionName')
db.<collection>.insertOne({...})
db.<collection>.updateOne({...})
db.<collection>.deleteOne({...})

4. _id field is automatically created and indexed
5. Using MongoDb in NodeJS
   • mongodb package
   • Creating a connection
   • Closing a connection