Agile Web Development with Rails, Edition 5

6.1 Iteration A1: Creating the Products Maintenance Application Table of Contents

2 Instant Gratification

We start with a simple "hello world!" demo application and in the process verify that everything is installed correctly.

Create the application

bundle exec /home/rubys/git/rails/railties/exe/rails new demo1 --skip-bundle --skip-listen
      create  
      create  README.md
      create  Rakefile
      create  config.ru
      create  .gitignore
      create  Gemfile
         run  git init from "."
Initialized empty Git repository in /home/rubys/git/awdwr/edition4/work-226-51/demo1/.git/
      create  app
      create  app/assets/config/manifest.js
      create  app/assets/javascripts/application.js
      create  app/assets/javascripts/cable.js
      create  app/assets/stylesheets/application.css
      create  app/channels/application_cable/channel.rb
      create  app/channels/application_cable/connection.rb
      create  app/controllers/application_controller.rb
      create  app/helpers/application_helper.rb
      create  app/jobs/application_job.rb
      create  app/mailers/application_mailer.rb
      create  app/models/application_record.rb
      create  app/views/layouts/application.html.erb
      create  app/views/layouts/mailer.html.erb
      create  app/views/layouts/mailer.text.erb
      create  app/assets/images/.keep
      create  app/assets/javascripts/channels
      create  app/assets/javascripts/channels/.keep
      create  app/controllers/concerns/.keep
      create  app/models/concerns/.keep
      create  bin
      create  bin/bundle
      create  bin/rails
      create  bin/rake
      create  bin/setup
      create  bin/update
      create  bin/yarn
      create  config
      create  config/routes.rb
      create  config/application.rb
      create  config/environment.rb
      create  config/secrets.yml
      create  config/cable.yml
      create  config/puma.rb
      create  config/spring.rb
      create  config/environments
      create  config/environments/development.rb
      create  config/environments/production.rb
      create  config/environments/test.rb
      create  config/initializers
      create  config/initializers/application_controller_renderer.rb
      create  config/initializers/assets.rb
      create  config/initializers/backtrace_silencers.rb
      create  config/initializers/cookies_serializer.rb
      create  config/initializers/cors.rb
      create  config/initializers/filter_parameter_logging.rb
      create  config/initializers/inflections.rb
      create  config/initializers/mime_types.rb
      create  config/initializers/new_framework_defaults_5_1.rb
      create  config/initializers/wrap_parameters.rb
      create  config/locales
      create  config/locales/en.yml
      create  config/boot.rb
      create  config/database.yml
      create  db
      create  db/seeds.rb
      create  lib
      create  lib/tasks
      create  lib/tasks/.keep
      create  lib/assets
      create  lib/assets/.keep
      create  log
      create  log/.keep
      create  public
      create  public/404.html
      create  public/422.html
      create  public/500.html
      create  public/apple-touch-icon-precomposed.png
      create  public/apple-touch-icon.png
      create  public/favicon.ico
      create  public/robots.txt
      create  test/fixtures
      create  test/fixtures/.keep
      create  test/fixtures/files
      create  test/fixtures/files/.keep
      create  test/controllers
      create  test/controllers/.keep
      create  test/mailers
      create  test/mailers/.keep
      create  test/models
      create  test/models/.keep
      create  test/helpers
      create  test/helpers/.keep
      create  test/integration
      create  test/integration/.keep
      create  test/test_helper.rb
      create  test/system
      create  test/system/.keep
      create  test/application_system_test_case.rb
      create  tmp
      create  tmp/.keep
      create  tmp/cache
      create  tmp/cache/assets
      create  vendor
      create  vendor/.keep
      create  package.json
      remove  config/initializers/cors.rb
      remove  config/initializers/new_framework_defaults_5_1.rb
bundle install --local
Resolving dependencies...
Using rake 12.0.0
Using pg 0.19.0
Using ffi 1.9.18
Using concurrent-ruby 1.0.5
Using i18n 0.8.4
Using minitest 5.3.3
Using thread_safe 0.3.6
Using builder 3.2.3
Using erubi 1.6.0
Using mini_portile2 2.1.0
Using rack 2.0.3
Using nio4r 2.1.0
Using websocket-extensions 0.1.2
Using mime-types-data 3.2016.0521
Using arel 8.0.0
Using bundler 1.15.1
Using method_source 0.8.2
Using thor 0.19.4
Using sqlite3 1.3.13
Using puma 3.9.0
Using sass 3.4.24
Using tilt 2.0.7
Using execjs 2.7.0
Using coffee-script-source 1.12.2
Using turbolinks-source 5.0.3
Using multi_json 1.12.1
Using byebug 9.0.6
Using public_suffix 2.0.5
Using rubyzip 1.2.1
Using websocket 1.2.4
Using bindex 0.5.0
Using queue_classic 3.2.0.RC1 from source at `/home/rubys/git/queue_classic`
Using rb-inotify 0.9.9 from source at `/home/rubys/git/rb-inotify`
Using childprocess 0.7.0
Using tzinfo 1.2.3
Using nokogiri 1.7.2
Using rack-test 0.6.3
Using sprockets 3.7.1
Using websocket-driver 0.6.5
Using mime-types 3.1
Using uglifier 3.2.0
Using coffee-script 2.4.1
Using turbolinks 5.0.1
Using addressable 2.5.1
Using selenium-webdriver 3.4.0
Using activesupport 5.1.1 from source at `/home/rubys/git/rails`
Using loofah 2.0.3
Using xpath 2.1.0
Using mail 2.6.5
Using rails-dom-testing 2.0.3
Using globalid 0.4.0
Using activemodel 5.1.1 from source at `/home/rubys/git/rails`
Using jbuilder 2.6.4
Using spring 2.0.2
Using rails-html-sanitizer 1.0.3
Using capybara 2.14.0
Using activejob 5.1.1 from source at `/home/rubys/git/rails`
Using activerecord 5.1.1 from source at `/home/rubys/git/rails`
Using actionview 5.1.1 from source at `/home/rubys/git/rails`
Using actionpack 5.1.1 from source at `/home/rubys/git/rails`
Using actioncable 5.1.1 from source at `/home/rubys/git/rails`
Using actionmailer 5.1.1 from source at `/home/rubys/git/rails`
Using railties 5.1.1 from source at `/home/rubys/git/rails`
Using sprockets-rails 3.2.0
Using coffee-rails 4.2.2
Using web-console 3.5.1 from source at `/home/rubys/git/web-console`
Using rails 5.1.1 from source at `/home/rubys/git/rails`
Using sass-rails 5.0.6
Bundle complete! 16 Gemfile dependencies, 68 gems now installed.
Use `bundle info [gemname]` to see where a bundled gem is installed.

Start the server.

get /

Ruby on Rails

Yay! You’re on Rails!

Welcome

Rails version: 5.1.1
Ruby version: 2.2.6 (x86_64-linux)

See what files were created

ls -p
app/	 config.ru  Gemfile.lock  package.json	README.md  vendor/
bin/	 db/	    lib/	  public/	test/
config/  Gemfile    log/	  Rakefile	tmp/

Create a simple controller

rails generate controller Say hello goodbye
      create  app/controllers/say_controller.rb
       route  get 'say/goodbye'
       route  get 'say/hello'
      invoke  erb
      create    app/views/say
      create    app/views/say/hello.html.erb
      create    app/views/say/goodbye.html.erb
      invoke  test_unit
      create    test/controllers/say_controller_test.rb
      invoke  helper
      create    app/helpers/say_helper.rb
      invoke    test_unit
      invoke  assets
      invoke    coffee
      create      app/assets/javascripts/say.coffee
      invoke    scss
      create      app/assets/stylesheets/say.scss
edit app/controllers/say_controller.rb
class SayController < ApplicationController
  def hello
  end
 
  def goodbye
  end
end

Restart the server.

Attempt to fetch the file - note that it is missing

get /say/hello

Say#hello

Find me in app/views/say/hello.html.erb

Replace file with a simple hello world

edit app/views/say/hello.html.erb
<h1>Hello from Rails!</h1>

This time it works!

get /say/hello

Hello from Rails!

Add a simple expression

edit app/views/say/hello.html.erb
<h1>Hello from Rails!</h1>
<p>
  It is now <%= Time.now %>
</p>
get /say/hello

Hello from Rails!

It is now 2017-06-02 18:40:31 -0400

Evaluate the expression in the controller.

edit app/controllers/say_controller.rb
class SayController < ApplicationController
  def hello
    @time = Time.now
  end
 
  def goodbye
  end
end

Reference the result in the view.

edit app/views/say/hello.html.erb
<h1>Hello from Rails!</h1>
<p>
  It is now <%= @time %>
</p>
get /say/hello

Hello from Rails!

It is now 2017-06-02 18:40:31 -0400

Replace the goodbye template

edit app/views/say/goodbye.html.erb
<h1>Goodbye!</h1>
<p>
  It was nice having you here.
</p>
get /say/goodbye

Goodbye!

It was nice having you here.

Add a link from the hello page to the goodbye page

edit app/views/say/hello.html.erb
<h1>Hello from Rails!</h1>
<p>
  It is now <%= @time %>
</p>
<p>
  Time to say
  <%= link_to "Goodbye", say_goodbye_path %>!
</p>
get /say/hello

Hello from Rails!

It is now 2017-06-02 18:40:31 -0400

Time to say Goodbye!

Add a link back to the hello page

edit app/views/say/goodbye.html.erb
<h1>Goodbye!</h1>
<p>
  It was nice having you here.
</p>
<p>
  Say <%= link_to "Hello", say_hello_path %> again.
</p>
get /say/goodbye

Goodbye!

It was nice having you here.

Say Hello again.

Intentionally introduce a typo in the code

edit app/controllers/say_controller.rb
class SayController < ApplicationController
  def hello
    @time = Time.know
  end
 
  def goodbye
  end
end
get /say/hello

HTTP Response Code: 500

NoMethodError in SayController#hello

undefined method `know' for Time:Class

Extracted source (around line #4):
2
3
4
5
6
7
              
def hello
#START_HIGHLIGHT
@time = Time.know
#END_HIGHLIGHT
end

Rails.root: /home/rubys/git/awdwr/edition4/work-226-51/demo1

Application Trace | Framework Trace | Full Trace

Request

Parameters:

None

Response

Headers:

None

Intentionally introduce a typo in a URL

get /say/hullo

HTTP Response Code: 404

Routing Error

No route matches [GET] "/say/hullo"

Rails.root: /home/rubys/git/awdwr/edition4/work-226-51/demo1

Application Trace | Framework Trace | Full Trace

Routes

Routes match in priority from top to bottom

Helper HTTP Verb Path Controller#Action
Path / Url
say_hello_path GET /say/hello(.:format)

say#hello

say_goodbye_path GET /say/goodbye(.:format)

say#goodbye

Request

Parameters:

None

Response

Headers:

None

6.1 Iteration A1: Creating the Products Maintenance Application Table of Contents