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Ruby on Rails by Manik Juneja
• Rails is a Web Application development framework.
• Based on the MVC pattern
• Gives a pure Ruby development environment
• Created by DHH of 37signals.
• Is open source
• Some sites running on RoR are basecamp, tadalist, writeboard, Campfire, 43things, odeo, Blinksale, Bubbleshare, Calendarhub, Nativetext, Numsum, Sproutit, Suprglu
• Some open source applications built on RoR are typo, hieraki2
About Rails
Ruby on Rails by Manik Juneja
Rail’s Philosophy
– DRY( Don’t Repeat Yourself) •Every piece of knowledge should be expressed in just one place
– Convention over configuration •Sensible defaults for just about every aspect of your application. If you need to overwrite the convention Rails makes that easy too.
The MVC architecture
Ruby on Rails by Manik Juneja
Model stores the state of the application
Sometime this state is
• Transient (Session)
• Permanent (database)
Model = data + business rules that apply to it.
What is a Model?
Ruby on Rails by Manik Juneja
DB is relational Ruby is Object Oriented
Table Class
Row Object
Columns Attributes
Table Level operations Class Methods
Row Level operations Object Methods
ActiveRecord Module provides ORM in Rails.
Model: Object Relational Mapping
Ruby on Rails by Manik Juneja
ActiveRecord: Getting Started
1. Specify database access details in config/database.yml file
2. Create a subclass of ActiveRecord::Base class
3. Give it a name. (By default, Active Record assumes that the name of the table is the plural form of the name of the class. By default id is the primary key )
Ruby on Rails by Manik Juneja
ActiveRecord: Other Features
• Transaction Handling
• Acts as (list, tree)
• Aggregation
• Validation
• Callback
• etc
Ruby on Rails by Manik Juneja
ActionPack : where the action happens
Action Pack lies at the heart of Rails applications. It consists of two Ruby modules, ActionController and ActionView. Together, they provide support for processing incoming requests and generating outgoing responses.
Ruby on Rails by Manik Juneja
Controller orchestrates the application
• Receives external input
• Processes internal action
• Responds to user
Receives external input
In the form of a url like http://mysite.com/user/show/1
File config/routes.rb, is used to map external requests to internal actions.
ActionController
controller user
action show
id 1
Ruby on Rails by Manik Juneja
Controller looks for a public instance method with the same name as the incoming action
ActionController: action
Controller has access to the execution environment via objects such as request, params, response, cookies, session, header
Ruby on Rails by Manik Juneja
ActionController : filterFilters enable wrapping of controllers’ actions — you can write a chunk of code once and have called before or after any number of actions in your controller
This is very useful in authentication, logging etc.
Ruby on Rails by Manik Juneja
The ActionView module encapsulates the functionality needed to render templates.
A Template is text embedded with ruby code ( in erb tags <% ….. %>
All instance variables of the controller are available in the template.
ActionView
Ruby on Rails by Manik Juneja
Honoring DRY
Many pages share the same header, footer, sidebar (use layouts)
Multiple pages may contain same snippet of rendered HTML (use partials)
Same functionality may appear on multiple pages ( use components )
Layouts, Partials, Components
Ruby on Rails by Manik Juneja
Rails has inbuilt pagination support at both controller and view level
Pagination
Ruby on Rails by Manik Juneja
Rails has inbuilt support for Ajax
1. It has prototype, effects, drag drop and control JavaScript libraries built in.
2. JavaScriptHelper module which wrap JavaScript access in ruby code.
Ajax on Rails
Ruby on Rails by Manik Juneja
Must Mention, before I Thank You
•Action Mailer
•Action Web Service
•Testing Framework
•Rake