Users Resource$
rails generate scaffold User name:string
email:string #id will be generated
automatically as primary key invoke active_record $ bundle exec rake db:migrate # migrate the database using Rakecreate db/migrate/20130715233046_create_users.rb create app/models/user.rb invoke test_unit create test/models/user_test.rb create test/fixtures/users.yml invoke resource_route route resources :users invoke scaffold_controller create app/controllers/users_controller.rb invoke erb create app/views/users create app/views/users/index.html.erb create app/views/users/edit.html.erb create app/views/users/show.html.erb create app/views/users/new.html.erb create app/views/users/_form.html.erb invoke test_unit create test/controllers/users_controller_test.rb invoke helper create app/helpers/users_helper.rb invoke test_unit create test/helpers/users_helper_test.rb invoke jbuilder create app/views/users/index.json.jbuilder create app/views/users/show.json.jbuilder invoke assets invoke coffee create app/assets/javascripts/users.js.coffee invoke scss create app/assets/stylesheets/users.css.scss invoke scss create app/assets/stylesheets/scaffolds.css.scss == CreateUsers: migrating ==================================================== -- create_table(:users) -> 0.0210s == CreateUsers: migrated (0.0211s) =========================================== Notes:Rake is Ruby make, a make-like language written in Ruby. $ bundle exec rake -T db $ bundle exec rake -T
Add a new user (The green welcome message is accomplished using the flash) 
REpresentational State Transfer (REST)
If you read much about Ruby on Rails web development, you’ll see a lot of references to “REST”, which is an acronym for REpresentational State Transfer. REST is an architectural style for developing distributed, networked systems and software applications such as the World Wide Web and web applications. Although REST theory is rather abstract, in the context of Rails applications REST means that most application components (such as users and microposts) are modeled as resources that can be created, read, updated, and deleted—operations that correspond both to the CRUD operations of relational databases and four fundamental HTTP request methods: POST, GET, PATCH, and DELETE. (We’ll learn more about HTTP requests in Section 3.2.1 and especially Box 3.3.) Model inherits from active record. Variables that start with the @ sign, called instance variables, are automatically available in the view;Microposts Resource$ rails generate scaffold Micropost content:string user_id:integer invoke active_record $ bundle exec rake db:migratecreate db/migrate/20130716191611_create_microposts.rb create app/models/micropost.rb invoke test_unit create test/models/micropost_test.rb create test/fixtures/microposts.yml invoke resource_route route resources :microposts invoke scaffold_controller create app/controllers/microposts_controller.rb invoke erb create app/views/microposts create app/views/microposts/index.html.erb create app/views/microposts/edit.html.erb create app/views/microposts/show.html.erb create app/views/microposts/new.html.erb create app/views/microposts/_form.html.erb invoke test_unit create test/controllers/microposts_controller_test.rb invoke helper create app/helpers/microposts_helper.rb invoke test_unit create test/helpers/microposts_helper_test.rb invoke jbuilder create app/views/microposts/index.json.jbuilder create app/views/microposts/show.json.jbuilder invoke assets invoke coffee create app/assets/javascripts/microposts.js.coffee invoke scss create app/assets/stylesheets/microposts.css.scss invoke scss identical app/assets/stylesheets/scaffolds.css.scss == CreateMicroposts: migrating =============================================== -- create_table(:microposts) -> 0.0281s == CreateMicroposts: migrated (0.0281s) ====================================== To put constaints on model e.g. maximum size of a field $ vim ./app/models/micropost.rb class Micropost < ActiveRecord::Base validates :content, length: { maximum: 140 } end $ vim app/models/user.rb class User < ActiveRecord::Base has_many :microposts end $vim app/models/micropost.rb class Micropost < ActiveRecord::Base belongs_to :user validates :content, length: { maximum: 140 } end Test in Relation in Rails Console$ rails console >> firstUser = User.first >> firstUser.microposts # association facilities in Active Record >> exit OR Ctrl+d It is by inheriting from ActiveRecord::Base that our model
objects gain the ability to communicate with the database, treat the
database columns as Ruby attributes, and so on.
by inheriting ultimately from ActionController::Base both
the Users and Microposts controllers gain a large amount of
functionality, such as the ability to manipulate model objects, filter
inbound HTTP requests, and render views as HTML. Since all Rails
controllers inherit from ApplicationController, rules defined in the Application controller automatically apply to every action in the application.To deploy Listing 2.17. Configuring Rails to serve static assets in production.
config/environments/production.rb DemoApp::Application.configure do . . . config.serve_static_assets = true . . . end With the change in Listing 2.17, we’re now ready to push up to Heroku: $ git commit -a -m "Serve static assets" $ heroku create $ git push heroku master Finally, migrate the production database (see below if you get a deprecation warning): $ heroku run rake db:migrate
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