Agile Web Development with Rails, Edition 4

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/bin/rails new demo1 --skip-bundle
      create  
      create  README.rdoc
      create  Rakefile
      create  config.ru
      create  .gitignore
      create  Gemfile
      create  app
      create  app/assets/javascripts/application.js
      create  app/assets/stylesheets/application.css
      create  app/controllers/application_controller.rb
      create  app/helpers/application_helper.rb
      create  app/views/layouts/application.html.erb
      create  app/assets/images/.keep
      create  app/mailers/.keep
      create  app/models/.keep
      create  app/controllers/concerns/.keep
      create  app/models/concerns/.keep
      create  bin
      create  bin/bundle
      create  bin/rails
      create  bin/rake
      create  config
      create  config/routes.rb
      create  config/application.rb
      create  config/environment.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/backtrace_silencers.rb
      create  config/initializers/filter_parameter_logging.rb
      create  config/initializers/inflections.rb
      create  config/initializers/mime_types.rb
      create  config/initializers/secret_token.rb
      create  config/initializers/session_store.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/favicon.ico
      create  public/robots.txt
      create  test/fixtures
      create  test/fixtures/.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  tmp/cache
      create  tmp/cache/assets
      create  vendor/assets/javascripts
      create  vendor/assets/javascripts/.keep
      create  vendor/assets/stylesheets
      create  vendor/assets/stylesheets/.keep
bundle install --local
Resolving dependencies...
Using rake 11.1.2
Using i18n 0.7.0
Using minitest 4.7.5
Using multi_json 1.12.0
Using thread_safe 0.3.5
Using tzinfo 0.3.49
Using builder 3.1.4
Using erubis 2.7.0
Using rack 1.5.5
Using mime-types-data 3.2016.0221
Using activerecord-deprecated_finders 1.0.4
Using arel 4.0.2.20140205180311 from source at `/home/rubys/git/arel`
Using bundler 1.12.2
Using coffee-script-source 1.10.0
Using execjs 2.6.0
Using thor 0.19.1
Using hike 1.2.3
Using json 1.8.3
Using tilt 1.4.1
Using sass 3.2.19
Using sqlite3 1.3.11
Using activesupport 4.0.13 from source at `/home/rubys/git/rails`
Using rack-test 0.6.3
Using mime-types 3.0
Using coffee-script 2.4.1
Using uglifier 3.0.0
Using rdoc 4.2.2
Using sprockets 2.12.4
Using activemodel 4.0.13 from source at `/home/rubys/git/rails`
Using jbuilder 1.5.3
Using actionpack 4.0.13 from source at `/home/rubys/git/rails`
Using mail 2.6.4
Using sdoc 0.4.1
Using activerecord 4.0.13 from source at `/home/rubys/git/rails`
Using railties 4.0.13 from source at `/home/rubys/git/rails`
Using sprockets-rails 2.3.3 from source at `/home/rubys/git/sprockets-rails`
Using actionmailer 4.0.13 from source at `/home/rubys/git/rails`
Using coffee-rails 4.0.1
Using jquery-rails 3.1.4
Using sass-rails 4.0.5
Using rails 4.0.13 from source at `/home/rubys/git/rails`
Using turbolinks 2.5.3
Bundle complete! 11 Gemfile dependencies, 42 gems now installed.
Use `bundle show [gemname]` to see where a bundled gem is installed.

See what files were created

ls -p
app/  config/	 db/	  Gemfile.lock	log/	 Rakefile     test/  vendor/
bin/  config.ru  Gemfile  lib/		public/  README.rdoc  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
      create      test/helpers/say_helper_test.rb
      invoke  assets
      invoke    coffee
      create      app/assets/javascripts/say.js.coffee
      invoke    scss
      create      app/assets/stylesheets/say.css.scss
edit app/controllers/say_controller.rb
class SayController < ApplicationController
  def hello
  end
 
  def goodbye
  end
end

Start 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 2016-05-06 09:40:33 -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 2016-05-06 09:40:33 -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 2016-05-06 09:40:33 -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-224-40/demo1

Application Trace | Framework Trace | Full Trace 
app/controllers/say_controller.rb:4:in `hello'

Request

Parameters:

None
Toggle session dump
Toggle env dump

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-224-40/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

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