1) From Zero To Deploy

Prereq

Some interesting tidbits about Ruby functions that you should know to understand syntax such as render html: "hello, world!". Putting that is the same as passing {:html => "hello, world!"} as the first arg ie render({:html => "hello, world!"})

irb(main):018:0> def test(obj)
irb(main):019:1> obj[:to]
irb(main):020:1> end
=> :test
irb(main):021:0> test to: 'hello'
=> "hello"
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See this post for more information.

As for the fact that you can alias root in the router as root to: 'controller#action', this is because of how they handle the argument in the source code:

def root(path, options = {})
  if path.is_a?(String)
    options[:to] = path
  elsif path.is_a?(Hash) && options.empty?
    options = path
  else
    raise ArgumentError, "must be called with a path and/or options"
  end
  # the rest is omitted for brevity
  options
end

irb(main):072:0> root 'override'
=> {:to=>"override"}
irb(main):038:0> root path: 'testing'
=> {:path=>"testing"}
irb(main):039:0> root to: 'testing'
=> {:to=>"testing"}
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You could use keywords args to explore/enforce the explicit use of path: in the call.

def root(path:, options = {})
  if path.is_a?(String)
    options[:to] = path
  elsif path.is_a?(Hash) && options.empty?
    options = path
  else
    raise ArgumentError, "must be called with a path and/or options"
  end
  # the rest is omitted for brevity
  options
end

# Note that the first call is now considered a string
irb(main):024:0> root path: 'testing'
=> {:to=>"testing"}
irb(main):026:0> root path: {:to => 'testing'}
=> {:to=>"testing"}
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Up and Running

You have the choice of getting up and running with Cloud9 or locally.

For local, run bundle init. It will create a Gemfile in the current directory.

Change Gemfile to install Rails and then run bundle install to grab the required gems.

You can confirm Rails has installed with rails -v and create a new rails app into hello_app by running rails _6.1.0_ new hello_app where _6.1.0_ is the optional version to use to scaffold the app. You will see the response in the console for a number of files being created and a Gem installation happening.

The scaffolded files include:

Change into the scaffolded folder cd hello_app.

In the app we are using, there is going to be an explicit Gemfile that we wish to use:

source 'https://rubygems.org'
git_source(:github) { |repo| "https://github.com/#{repo}.git" }

gem 'rails',      '6.1.0'
gem 'puma',       '5.0.4'
gem 'sass-rails', '6.0.0'
gem 'webpacker',  '4.2.2'
gem 'turbolinks', '5.2.1'
gem 'jbuilder',   '2.10.0'
gem 'bootsnap',   '1.4.6', require: false

group :development, :test do
  gem 'sqlite3', '1.4.2'
  gem 'byebug',  '11.1.3', platforms: [:mri, :mingw, :x64_mingw]
end

group :development do
  gem 'web-console',           '4.1.0'
  gem 'listen',                '3.2.1'
  gem 'spring',                '2.1.1'
  gem 'spring-watcher-listen', '2.0.1'
end

group :test do
  gem 'capybara',           '3.32.2'
  gem 'selenium-webdriver', '3.142.7'
  gem 'webdrivers',         '4.3.0'
end

# Windows does not include zoneinfo files, so bundle the tzinfo-data gem
# Uncomment the following line if you're running Rails
# on a native Windows system:
# gem 'tzinfo-data', platforms: [:mingw, :mswin, :x64_mingw, :jruby]
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Run bundle install to install those gems. You may get a message requiring bundle update if you have conflicts with the Gem lockfile Gemfile.lock.

rails server

The rails server command will get a webserver up and running. Run that to get things up and running.

Once running, if you head to http://localhost:3000 you will get the welcome page.

The welcome page includes the Rails version, as well as the Ruby version on your system.

Model-View-Controller (MVC)

This follows the MVC pattern which conveniently alligns with subfolders of app/ aptly named models, views and controllers.

For a short excerpt overview of interaction with the Rails application, we have the following:

When creating a new project, you only start with one controller: the application controller. You can confirm this by running ls app/controllers/*_controller.rb.

Update the controller to take a new hello method:

class ApplicationController < ActionController::Base
  def hello
    render html: "hello, world!"
  end
end
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Now that we have the action to return the desired stringm we need to tell Rails to use that action instead of the default page. We will need to edit the router (which sits in front of the controller)

We will need to head to config/routes.rb where it can direct us to the routing guide on the Rails website to learn more about routing.

On the webpage under `#using-root, it informs us that you can specify where / should route to with the root method.

We can do this with root to: 'controller_name#action_name which in shorthand is root 'controller_name#action_name'.

And so, we update the page like so:

Rails.application.routes.draw do
  # For details on the DSL available within this file, see https://guides.rubyonrails.org/routing.html
  root "application#hello"
end
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For future reference, you can also specify a root within a namespace like so:

namespace :admin do
  root to: "admin#index"
end
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Deploying on Heroku

Heroku uses PostgreSQL, so we need to add the PostgreSQL gem for production use:

group :production do
  gem 'pg', '1.2.3'
end
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You should also move the sqlite3 gem to :development to ensure it is not included in the production environment.

To bundle without production gems, you run bundle install --without production. More recent versions of Bundler will ask you to run bundle config set without 'production' && bundle install.

For the deployment of Heroku, you will to have a Heroku account and setup the Heroku CLI. On MacOS you can do this via Brew brew install heroku/brew/heroku.

Once installed, run heroku login --interactive for the interactive login process.

After logging in, create a new application with heroku create.

To run the deploy, we need to use Git to push the master branch to Heroku with git push heroku main (or master if you are using master).

Finally, run heroku apps:info to get the information and web URL for your deployment!

Heroku Commands