Getting Started

RubyGems

RubyGems is a package manager for the Ruby programming language that provides a standard format for distributing Ruby programs and libraries (in a self-contained format called a "gem"), a tool designed to easily manage the installation of gems, and a server for distributing them. – https://en.wikipedia.org/wiki/RubyGems

RubyGems is a tool to install other people's code.

Update RubyGems

RubyGems come with Ruby, has a command called gem. Update it to latest version:

$> gem update --system

RubyGems Commands

$> gem -v

$> gem list

$> gem search xls
$> gem install axlsx 

$> gem search rubyzip
$> gem install rubyzip

Where to find more RubyGems

• The Ruby Toolbox
• BestGems
• micro.rb

Bundler

Bundler is another RubyGem. Bundler provides a consistent environment for Ruby projects by tracking and installing the exact gems and versions that are needed.

Those dependencies are listed in a file called Gemfile. Bundler will resolve dependencies automatically for you.

Run a command:

bundle install

Bundler will ensure that the gems you need are present in all environments.

Starting work on a project is as simple as bundle install.

Ruby on Rails

Books

• Ruby on Rails Doctrine
• Agile web development with Rails

What is Rails?

A web framework created by David Heinemeier Hansson (known as DHH). Partner of Basecamp (formerly 37 Signals). A developer, writer, and race car driver.

Rails History

Over 10 years of Rails. 57000+ commits with 4300+ contributors and 280+ versions. Milestones:

Rails Philosophy

• Convention over Configuration
• Don't Repeat Yourself
• Agile
• MVC

Rails Architecture

• Action View
• Action Dispatcher
• Action Controller
• Active Record
• Action Mailer
• Active Job
• Active Support

Scaffold

Use rails scaffold to create a CRUD (Create, Read, Update, Delete).

rails new shop --skip-test-unit --database=postgresql

View available options like --skip-test-unit and --database options by typing rails.

• What is --skip-test-unit?
• What is --database?
• bundle install Rails is a framework around various libraries.

View scaffold usage by typing: rails generate scaffold.

rails generate scaffold product name:string description:text price:integer

Then create and migrate the database:

rake db:create db:migrate

Fires up the Rails:

rails server

Open http://localhost:3000/products in your browser and click around.

We are done with the Feature!

But let's take a step back, to see what we just accomplished.

• rails is a command
• generate is a subcommand of rails, to generate files (scaffold, migration)
• scaffold tells generate what to generate here
• and the rest (name:string description:text price:integer) are the attributes of this "thing"

Scaffold is kind of CRUD. For any web applications you want to do. Identify CRUD stuff.

Examples:

• Facebook
• Airbnb
• Twitter
• Blog
• Search

What are the CRUD in these applications?

Once you have this, you are halfway there. Next would be workflows.

Deep dive into scaffold

Let’s go through what scaffold just did.

• In order to CRUD product, we need models, views, controllers and routes
• Naming Conventions (controllers vs. views vs. models vs database tables)

What we have done is to let Rails generate all these files for us.

Scaffold Magic for CRUD!

In Production quality code, we avoid using scaffold. And generate each of these files ourselves, as and when we need them!

# Model
      invoke  active_record
      create    db/migrate/20140507125949_create_products.rb
      create    app/models/product.rb
# Route
      invoke  resource_route
       route    resources :products
# Controller
      invoke  scaffold_controller
      create    app/controllers/products_controller.rb
# View
     invoke    erb
      create      app/views/products
      create      app/views/products/index.html.erb
      create      app/views/products/edit.html.erb
      create      app/views/products/show.html.erb
      create      app/views/products/new.html.erb
      create      app/views/products/_form.html.erb
      invoke    helper
      create      app/helpers/products_helper.rb
      invoke    jbuilder
      create      app/views/products/index.json.jbuilder
      create      app/views/products/show.json.jbuilder
      invoke  assets
      invoke    coffee
      create      app/assets/javascripts/products.js.coffee
      invoke    scss
      create      app/assets/stylesheets/products.css.scss
      invoke  scss
      create    app/assets/stylesheets/scaffolds.css.scss

Watch the singular and plural forms:

• Migration: db/migrate/20140507125949createproducts.rb
• Model: app/models/product.rb
• Route: resources :products
• Controller: app/controllers/products_controller.rb
• View:
  • app/views/products
  • app/views/products/index.html.erb
  • app/views/products/edit.html.erb
  • app/views/products/show.html.erb
  • app/views/products/new.html.erb
  • app/views/products/_form.html.erb
• Helper: app/helpers/products_helper.rb
• jbuilder:
  • app/views/products/index.json.jbuilder
  • app/views/products/show.json.jbuilder
• Assets:
  • app/assets/javascripts/products.js.coffee
  • app/assets/stylesheets/products.css.scss

Any rails command is reversible, for example to undo the rails generate scaffold:

rails destroy scaffold product