Rails and Grails

1. Rails and Grails

2. To get started • Make sure you have java installed • You can get the sdk and jre at: http://www.oracle.com/technetwork/java/javase/downloads/java-se-jdk-7-download-432154.html • Install the jdk and not just the jre

3. Ruby on Rails • Context • Website development is highly repetitive • The client side has been addressed with a number of tools that support drag and drop, adjustable technology, often xml-based • But the rest of the process remained fairly tedius • Goal of various web development frameworks • Provide a top down approach to building db-centric web apps • Remove a lot of configuration detail work • Generate the core of the back end code using MVC • Hide the db from the developer and provide a more uniform approach, language-wise, for building a web app • Tradeoff – programmer loses a lot of control over the architecture of the web app

4. Install Rails • Go to http://www.ruby-lang.org/en/downloads/ • Choose your platform and • install the ruby language • install “ruby gems” • windows, use the installer at http://rubyinstaller.org/ • Install RubyMine: http://www.jetbrains.com/ruby/quickstart/ • Go to Settings on RubyMine • Tell it where your ruby installation is • Install the gem called “bundler” • It helps install other gems • Run update on all your gems

5. Create a project • Use File to create a new “rails application” in RubyMine • Set it up for mysql – RubyMine will do this for you • Call it first_project- You should get this:

6. Your project folder • App folder • Has your controllers, models, and views in it • Remember to save it frequently • Config folder • Has database.yml file – note that the default is sqlite • This is why you had RubyMine use mysql • Notice that there are 3 databases in an official RonR app • Development, test, production • Use development, you don’t need to build the other dbs

7. Your database • Turn on your mysql and apache • Create a database called first_project_development • No need to create any tables… • You may need to put this in your ruby/bin folder: • You can get it here – • http://dev.mysql.com/get/Downloads/Connector-C/mysql-connector-c-noinstall-6.0.2-win32.zip/from/pick

8. Run your app You should get this:

9. Click on the blue words and get:

10. MVC RonR subdirectories • The controllers subdirectory. A controller handles a web request from the user. • The views subdirectory holds the display templates to fill in with data and return data to the user's browser. • The models subdirectory holds the classes that define the data being manipulated • The helpers subdirectory holds helper classes used to assist the model, view, and controller classes. The idea is to keep the m, v, and c classes minimal.

11. Rails tutorial: Assignment 9Due on Dec 11. • See: http://ruby.railstutorial.org/ruby-on-rails-tutorial-book?version=3.2 for a very detailed tutorial • And see: https://github.com/perfectionist/sample_project/wiki/Using-RubyMine-IDE-for-Ruby-on-Rails-Tutorial for instructions on how to use RubyMine for the tutorial • Tutorial assignment: build the demo app described in chapter 2 of the tutorial document: http://ruby.railstutorial.org/chapters/a-demo-app?version=3.2#top • Hand in a zipped up project folder. I don’t need the database. Include a screen snapshot of your project folder in RubyMine. • Important: this material will be on the final. • Note: if you have problems with any details of the tutorial you can skip them – the important thing is to learn the concepts and to do most of the tutorial.

12. Some things to think about as you do the RonR tutorial… • What is Active Record? • An abstraction layer that sits on top of relational databases • Provides an easy way to move between relational platforms • Relies on a single .yml file • The idea is that you do not write SQL, at least not directly • You can retrieve objects: http://guides.rubyonrails.org/active_record_querying.html • You can add, change, delete tables using “migrations” http://guides.rubyonrails.org/migrations.html NOTE: The link to the guides as a whole is: http://guides.rubyonrails.org/ … What do you think of the Active Record paradigm?

13. Active records • This is a form of object to relational mapping • Active record connects ruby classes to db tables • It is installed with “gem install activerecord”, or via RubyMine • See: http://api.rubyonrails.org/files/activerecord/README_rdoc.html • The classes are the “models” that map to tables • “Views” are html pages with embedded ruby • “Controllers” are ruby scripts • Restrictions (conventions) • Class names are singular • Table names are plural • Tables contain and identity column named id • If you use underscores _ in your table name, you leave them out on the class name • Active record supports CRUD • Create, read, update, delete primitives

14. More Ruby on Rails questions • What are “migrations”? • They are a structured and database product • Database independent (e.g., MySQL versus Oracle) way of creating and maintaining a database while you build a site • Look at: http://guides.rubyonrails.org/migrations.html • What is Rake? • It is a build tool inspired by Make • What is “scaffolding”? • This is what gives you the framework of an entire website in a snap, making it easy to orient yourself and show something to a customer early on in the website development process • You can create basic templates for views, controllers, and models … What do you think of migrations and scaffolding?

15. Active records primitives • create_table • change_table • drop_table • add_column • change_column • rename_column • remove_column • add_index • remove_index

16. Important construct: generators • These are rails commands that can be used to create pieces of a website • Generators often initiate other operations • Example $ rails generate scaffold User name:string results in the following generated code:  invoke  active_record db/migrate/20091120125558_create_users.rb       create    app/models/user.rb      invoke    test_unit   create      test/unit/user_test.rb     create      test/fixtures/users.yml route  resources :users

17. Example continued invokescaffold_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/functional/users_controller_test.rb       invoke    helper       create      app/helpers/users_helper.rb       invoke      test_unit       create        test/unit/helpers/users_helper_test.rb       invoke  stylesheets       create    app/assets/stylesheets/scaffold.css

18. Ruby on rails app servers • Native ruby webserver: Webrick and needs no configuration, and it is really only a web server (HTTP) • Lighttpd is a web server that focuses on speed and low memory usage • You can use Apache • There is growing use of Phusion: https://www.phusionpassenger.com/

19. Installing groovy and grails • Go to http://groovy.codehaus.org/ and install groovy • Make sure to let your OS create a system variable so groovy can be found • Go to http://grails.org/download and download grails, then open it up in one of your user folders (e.g., documents) • Open up Intellij • Turn on the grails plugin in the plugins settings in File/Settings • Create a grails project; you will be asked to point Intellij to your grails folder • You will be asked if you are developing an app or a plugin; choose app • By default, Grails uses an in memory database called HSQLDB. • Hibernate is a widely used object/relational mapping layer that is similar in purpose to Active Record

20. Grails tutorial: Assignment 10Due on Dec. 11 • You will discover a system of folders has been created, and it looks very much like ruby on rails • The datasource.groovy file is where you set up mysql or other database • The tutorial to follow is at: http://wiki.jetbrains.net/intellij/Creating_a_simple_Grails_application_with_IntelliJ_IDEA • This is much simpler than the RonR tutorial. • Submit: your final grails project, zipped up. I do not need the database. Include a screen snapshot of your Grails project in Intellij. • Important: this material will be on the final. • …something to think about: how is Grails different from Ruby on Rails?

21. Extra credit on Grails projecct • Get your grails project working with mysql and show it to me! • Hint: • You need to change the DataSource.groovy code • And --- you need to change BuildConfig.groovy code