Ruby on Rails

1
Ruby on Rails

• Building Web Applications Is Fun Again!

2
What is Ruby on Rails?

• Web application framework written in Ruby
• Ruby is an Object Oriented scripting language
• Model-view-controller
• Database agnostic
• Open source
• Lots of nice tools, classes and methods to make
  development easier

3
The Rails Way

• DRY (Dont Repeat Yourself)
• Convention over configuration
• Baked in testing
• Minimal code with maximum effect

4
Getting Started

• Installing Ruby, Gem and Rails
• Install Ruby OCI8 Driver
• Connect using TNSNAMES.ORA
• Connect using InstantClient and a URL
• More information on wiki.rubyonrails.com

5
Rails on Oracle

• Key generation assumes sequences for each table
  with the name table_name_seq
• Sequence name can be changed using
  ActiveRecordBase.set_sequence_name
• Timezones and sub-second precision not supported
• More info http//wiki.rubyonrails.com/rails/pages
  /Oracle

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Building Your First App

• Create a new Rails app by typing rails myapp
• Edit the config/database.yml
• Generate a model using script/generate model
  MyModel
• Creating a model creates a class and a migration

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ActiveRecord Conventions

• Naming convention simplifies development and
  encourages good database design
• Tables are plural, models are singular
• Example
• Model LineItem
• Table line_items
• Handles non-regular pluralization such as
  Person/people
• Can be overridden, although this complicates
  things for the developer

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Database Migrations

• Database agnostic means of defining schema
• Lowest-common-denominator approach
• Ruby code with full access to ActiveRecord
• Methods for creating, altering and dropping
  tables, columns and indexes
• Can execute arbitrary SQL with execute method

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ActiveRecord Models

• Object/Relational Mapping
• Model classes extend from ActiveRecordBase
• ActiveRecordBase provides
• Database agnostic record creation, finding,
  saving and removal
• Data validation methods
• Relationships
• All in an easy to use package
• Rails encourages keeping business logic in the
  model where it belongs
• AR can be used outside of web applications

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Views

• Responsible for creating part or all of the page
  displayed in a browser
• By default uses ERb (Embedded Ruby)
• Other views include builders for XML documents
  or RJS templates to generate JavaScript for AJAX
  driven views
• Includes elegant means for including helper
  functions for rendering
• Supports partials and components

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Controllers

• Generate controllers with script/generate
  controller MyController
• Controllers tie the view to the model through
  actions
• Controllers also have access to helpers
• Designed for people-friendly URLs
• Provides caching, session management, query
  parsing, cookie management, pagination

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ActiveRecord Relationships

• Relationships are through primary keys
• Supported relationship types
• belongs_to (book belongs to author)
• has_one (book has one publisher)
• has_many (book has many pages)
• has_and_belongs_to_many (book has and belongs to
  many readers)
• has_many through (book has many contributors
  through contributions)

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ActiveRecord Validation

• validates_presence_of
• validates_uniqueness_of
• validates_confirmation_of
• validates_acceptance_of
• validates_associated
• validates_each
• validates_format_of, _length_of
• validates_exclusion_of, _inclusion_of

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More ActiveRecord

• Acts As
• acts_as_list (position)
• acts_as_tree (parent_id)
• Aggregations
• composed_of
• Callbacks
• Full lifecycle
• Before and after validation, creation, saving,
  destroying
• Calculations
• average, count, maximum, minimum, sum

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Just When You Thought You Had Enough ActiveRecord

• Callback objects
• Observers
• Façade columns
• Object-level transaction management
• Magic column names
• created_on, created_at, updated_on, updated_at
  auto timestamping and dating
• lock_version and optimistic locking
• type for single table inheritence
• xxx_count counter cache

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Other Stuff

• ActionMailer for sending mail messages
• ActionView helpers
• Form helpers
• Asset tags
• Javascript support (yummy AJAX!)
• Pagination
• Text helpers
• ActionWebService
• Ruby language extensions
• Breakpoint and debugging

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Where To Go Next?

• http//www.rubyonrails.com/
• http//api.rubyonrails.com/
• http//wiki.rubyonrails.com/
• Agile Web Development with Rails
• http//www.ruby-doc.org/ for Ruby
• Programming Ruby
• IRC, Mailing Lists, Seth Ladds brain