rocketseat-bootcamp2020-module02

GoBarber Backend - Fundamental Concepts

What is this project about?

This project is about practicing the basic concepts behind NodeJS that were learned during the second module of GoStack 10 - Bootcamp.

How to run this project?

• Install dependencies:
  • yarn
• Start the back-end:
  • yarn dev

Logbook

Day 01 - 2020/02/21

Setting up the project structure

Docker Fundamentals

• How does it work?

  • Creates isolated environments (containers)
    • Isolated environments contains tools/technologies that will not change/edit our server's behaviour
    • Installing/updating/removing becomes too cumbersome through the traditional way
  • Containers expose communication ports

• Main Concepts

  • Image
    • It's a tool/technology (e.g.: MySQL, MongoDB) that can be placed inside a container
  • Container
  • It's an instance of an image
  • Docker Registry
    • Docker Hub
  • Dockerfile
    • 'recipe' to create your own customized docker image

Configuring Docker

• Creates an instance of PostgreSQL named postgresdb.

docker run --name postgresdb -e POSTGRES_PASSWORD=postgres -p 5432:5432 -d postgres

• Lists active container

docker ps

• Stops the container

docker stop postgresdb

• Lists all containers

docker ps -a

• Stars a container

docker start postgresdb

• Displays container logs

docker logs postgresdb

Sequelize & MVC

• ORM (Object Relational Mapper): way of abstracting a database

  • Changes the way the application communicates with the database

• Tables are now represented by Models

• Manipulate Data

  • No SQL (most of the time)
  • Only JavaScript code

  SELECT *
    FROM users 
    WHERE email="user@domain.com" 
    LIMIT 1

  User.findOne({
    where: {
      email: "user@domain.com"
    }
  })

• Migrations

  • Version control for databases
    • It's a way of maintaining the database updated
  • Each file contains instructions to create, edit, or delete tables or columns
  • Each file is a migration and migrations are ordered by date
  • What is a 'rollback'?
    • When you start a migration and something goes wrong you can perform a rollback, make changes to the table and start the migration again
    • When a migration is completed, it cannot be edited. Any required changes must be done through a new migration.
  • Every migration is specific to a table!

• Seeds

  • Populate the database with mock data for development
  • Used frequently to create data for testing
  • Executable only through code
  • Should never be used for production

• MVC Architecture

  • Model
    • Models are responsible for storing database abstractions
    • They are used to manipulate the data contained in the database
    • They have no responsability over our application's business rules
  • Controller
    • Controllers are the starting point of our application's requests
    • Routes are usually associated with a method from the controller
    • It's possible to include most of the application's business rules in the controllers
      • As the applications grows, business rules can be detached from the controllers
  • View
    • Views are what is being displayed to the client
    • In applications that don't use the REST API standard (JSON), that could be HTML

• More about Controllers

  • They are represented by Classes
  • Always return JSON
  • It will not invoke another controller/method
  • It should only contain 5 methods (index, show, store, edit, delete)

ESLint, Prettier & EditorConfig

• Tools that will maintaing the code standard

• ESLint

  • It will perform the 'linting' of the code.
  • Verifies if desired standards are being followed

    yarn eslint --init // Creates the configuration file
  

• Prettier

  • e.g.: Checks the sizes of lines of code

    yarn eslint --fix src --etx .js
  

• EditorConfig

  • It will help maintaining the same code standards/styles throughout different editors

User Migration

• Creates the migration file for the users table

  yarn sequelize migration:create --name=create-users

• Performs the migration

  yarn sequelize db:migrate

• Undo the last migration

  yarn sequelize db:migrate:undo

• Undo all migrations

  yarn sequelize db:migrate:undo:all

Day 02 - 2020/02/23

Creating Models Loader

• It will connect to the database and load our application's Models.
  • src/database/index.js

Generating Password Hash

• Generate password_hash
  • yarn add bcryptjs
• The field/attributes in the Model do not need to reflect 100% of what is in the database.
• Hooks are a Sequelize functionality
  • Parts of the code are executed automatically, based on the actions that are being performed by the Model

JWT (JSON Web Token) Concepts

• It's a way of authenticating in RESTful services

• JWT Authentication

  • [POST] http://api.com/sessions

    "email": "user@email.com",
    "password": "password"

• After user credentials are validated a JWT Token is generated for the user's session

• Structure of a JWT Token

  1. Headers (i.e.: what algorithm was used to generated the token)
  2. Payload (Additional data: id, name, email)
  3. Signature - (Makes sure the token cannot be edited)

JWT Authentication

• yarn add jsonwebtoken

• All jwt token has an expiry date

• src/config/auth.js

Authentication Middleware

• Update route can only be accessed by users that have been authenticated

  • It protects the route from being accessed by users that have not been previously authenticated

• A middleware must be used

  • It can be local or global. If it's a global middleware it will only be triggered by routes declared after it

• JWT Token must be sent through the header (e.g.: Bearer 7812yhdahsBysahjdahskdas...)

• src/app/middleware/auth.js

    const decode = await promisify(jwt.verify)(token, authCOnfig.secret);

Validating Data Input

• yarn add yup
  • Schema validation library
• import * as Yup from 'yup'
  • Does not has 'export as default'

  // An object will be validated (e.g.: req.body)
  // shape({}) represents the 'structure' the object needs to have
  const schema = Yup.object().shape({});