Ruby on Rails: Building Web Applications Is Fun Again!

Slide 1: Ruby on Rails Building Web Applications Is Fun Again! Presented by Anthony Eden

Slide 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

Slide 3: The Rails Way  DRY (Don’t Repeat Yourself)  Convention over configuration  Baked in testing  Minimal code with maximum effect

Slide 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

Slide 5: Rails on Oracle  Key generation assumes sequences for each table with the name ${table_name}_seq  Sequence name can be changed using ActiveRecord::Base.set_sequence_name  Timezones and sub-second precision not supported  More info: http://wiki.rubyonrails.com/rails/pages/Oracle

Slide 6: 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

Slide 7: 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

Slide 8: 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

Slide 9: ActiveRecord Models  Object/Relational Mapping  Model classes extend from ActiveRecord::Base  ActiveRecord::Base 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

Slide 10: 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

Slide 11: 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

Slide 12: 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)

Slide 13: 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

Slide 14: 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

Slide 15: 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

Slide 16: 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

Slide 17: 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 Ladd’s brain