Getting Started with Rails
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The document provides an overview of Ruby on Rails, a web application development framework that simplifies programming through conventions. It covers Rails' background, philosophy, app structure, and key components such as MVC pattern, Active Record, and routing, along with practical usage and assignments. Additionally, it introduces Ruby gems for extending functionality and includes useful links for further learning.
Getting Started with Rails
- 1. Getting started with By Basayel Said Rails
- 2. Points to cover .. ❏ What is Rails? ❏ Rails Background ❏ Rails Philosophy ❏ Who uses Rails? ❏ Rails App Structure ❏ MVC Pattern ❏ Rails Components ❏ What is Rake? ❏ What is a Gem? ❏ Useful Links ❏ Demo ( Blog Application ) ❏ Assignment
- 3. What is Rails? ● Rails is a web application development framework written in the Ruby language. It is designed to make programming web applications easier by making assumptions about what every developer needs to get started.
- 4. Rails Background ● David Hanson => BaseCamp, Ruby on Rails ● Hanson released Rails as open source in July 2004. ● December 2005, version 1 was released. ● Became very popular after Apple decided to bundle and ship it with their Mac OS X, Leopard, in October 2007.
- 6. Who uses Rails ?
- 7. Rails App Structure “app” Application Logic controllers, views, models, assets, … “config” Database, Routes & more configurations “db” Database schema & Migrations “public” static files & compiled assets “vendor” add-ons to “core” rails $ rails new Blog 12
- 8. MVC Pattern
- 10. Rails Components ● Models ○ Active Record Basics ○ Rails Database Migrations ○ Active Record Validations ○ Active Record Callbacks ○ Active Record Associations ○ Active Record Query Interface ● Views ○ Layouts and Rendering in Rails ○ Action View Form Helpers ● Controllers ○ Action Controller overview ○ Rails Routing from the outside in
- 11. Active Record
- 12. What is Active Record? ● Provides an interface and binding between the tables in a relational database and of the Ruby program code that manipulates database records ● Allows simple designs and straightforward mappings between database tables and application objects
- 13. Active Record Migrations A convenient way to alter your database schema over time in a consistent and easy way. They use a Ruby DSL so that you don't have to write SQL by hand, allowing your schema and changes to be database independent.
- 14. Active Record Validations As you can see, our validation lets us know that our Person is not valid without a name attribute. The second Person will not be persisted to the database. name field must have value
- 15. Active Record Validations ( More .. )
- 16. Active Record Callbacks Callbacks are methods that get called at certain moments of an object's life cycle. With callbacks it is possible to write code that will run whenever an ActiveRecord object is created, saved, updated, deleted, validated, or loaded from the database.
- 17. ActiveRecord Callbacks ( example )
- 18. Available Callbacks 3.1 Creating an Object before_validation after_validation before_save around_save before_create around_create after_create after_save 3.2 Updating an Object before_validation after_validation before_save around_save before_update after_update after_save 3.3 Destroying an Object before_destroy around_destroy after_destroy MORE ?!, Check http://guides.rubyonrails. org/active_record_callbacks. html
- 19. CRUD article = Article.new article.published = true article.save OR article = Article.create(published: true) Article.find(3) article = Article.find(3) article.subject = "Rails Tutorial” article.save OR article.update(subject: “Rails Tutorial”) article = Article.find(3) article.destroy Create Read Update Delete
- 20. Active Record Associations ( Why? )
- 21. Active Record Associations Rails supports six types of associations: ● belongs_to ● has_one ● has_many ● has_many :through ● has_one :through ● has_and_belongs_to_many
- 25. The has_many :through Association
- 27. The has_one :through Association
- 29. Active Record Query Interface
- 30. Active Record Query Interface (Cont.) MORE ?!, Check http://guides.rubyonrails.org/ active_record_querying.html
- 32. Layouts and Rendering Controller automatically render ➢ views with names corresponding to valid routes. ➢ {action_name}.html.erb
- 33. Layouts and Rendering for HTML, just use the defaults: get the view that is named the same as the action, and render it app/controllers/posts_controller.rb
- 34. Layouts and Rendering app/views/posts/index.html.erb embedded Ruby (.erb) automatically provided link helpers
- 37. Finding Layouts Rails first looks for a file in app/views/layouts with the same base name as the controller. Current Layout Application Layout Controller Layout Inheritance
- 39. form_tag ● Two arguments a. path for action : absolutely 1st argument b. options hash ■ HTTP method :post(default), :get, :put, :delete ■ HTML options :class, :style, ...
- 41. Helpers ● text_field_tag ● text_area_tag ● check_box_tag ● radio_button_tag ● password_field_tag ● hidden_field_tag ● search_field_tag ● url_field_tag ● email_field_tag Generating Form Elements HTML5 Controls MORE ?!, Check http://guides. rubyonrails.org/form_helpers.html
- 43. A Controller ● RESTful applications ● Like an orchestra conductor ● As a middleman between models & views
- 44. REST (URI with HTTP methods) GET /books HTTP/1.1 #index GET /books/new HTTP/1.1 #new GET /books/1 HTTP/1.1 #show POST /books HTTP/1.1 #create PUT /books/1 HTTP/1.1 #update GET /books/1/edit HTTP/1.1 #edit DELETE /books/1 HTTP/1.1 #destroy
- 45. Routing $ rake routes CONTROLLER=books named routes HTTP verbs resource URI Controllers & Actions
- 46. Methods & Actions ● A “class” has methods ● A controller < ApplicationController ● public methods => “action” <= routing Actions
- 47. Rake Rake a standalone Ruby utility ● Create a file .rake ● Run this rake file with the command rake my:alarm
- 48. What is a Gem? ● Extending functionalities with already packaged functions. ● i.e user authentication, message system, asset handlers, geolocation, pagination system, linking to exterior services such as Amazon AWS, and last but not least Rails itself) are called Ruby Gems ● Gems are ruby software packages ● Lots of gems can be found in github, but its funner to search for gems via ruby-gems or ruby-toolbox
- 49. Useful Links ➔ Ruby on Rails Guides ➔ Ruby on Rails Screencasts ➔ Rails Best Practices ➔ Rails Style Guide ➔ Testing Rails Applications ➔ Rails Tutorial Ebook by Michael Hartl
- 50. Hands On! Let’s create a Quick Blog Application
- 51. Assignment! Add the ability to comment on any post. While listing created comments for each post & a link to remove any comment Hint: Use Active Record Associations