1 / 11

A little engineering on Rails

A little engineering on Rails. Robert W. Hasker. Goals. Intro to the Rails framework Basic concepts: MVC, Active Record A bit of Ruby Using Rails to build a website Myths and issues. The Rails Framework. Basic goal: construct database-backed websites

niel
Download Presentation

A little engineering on Rails

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. A little engineering on Rails Robert W. Hasker

  2. Goals • Intro to the Rails framework • Basic concepts: MVC, Active Record • A bit of Ruby • Using Rails to build a website • Myths and issues

  3. The Rails Framework • Basic goal: construct database-backed websites • Multi-platform: popular OS’s, database engines • Origins: • Instiki by David Heinemeier Hansson • Basecamp by 37signals • Rails: domain-independent core • Built on the Ruby language • General-purpose language: scripting, applications • Dynamically typed, “open” classes

  4. Basic Concept: MVC • Issue: how to separate logic from presentation? • Classic solution: Model/View/Controller • Model: domain-level data • View: how the data is presented to the user • Typically want multiple views • Controller: logic linking the two • Rails • Model = tables in a relational database • View = web pages • Controller = controller

  5. Basic Concepts: Active Record • Relational Databases: organize large amounts of data • Issue: no easy mapping to object-oriented design • Active Record Pattern • A design pattern first described by Martin Fowler • Object = table row w/ attributes stored as columns • Table = collection of objects • OOD = database (collection of tables) • Rails: link classes through id fields in tables

  6. Active Record Example • Data for a simple voting system: • As tables: • create table questions (id int, body text, start datetime, end datetime, primary key(id)); • create table voters (id int, username text, password text, primary key(id)); • create table vote_records (voter_idint, …); • Benefit: can add operations as needed - active records

  7. Using rails to build a voting application • See http://www.uwplatt.edu/csse/tools/ruby/rails/rails-demo.html

  8. Conclusion • Rails: quick OO websites • MVC: sound organization • ActiveRecord: support good OO designs • Focus on relationships, not queries • Less likely to forget a join, but supports full SQL • Not shown: does support inheritance • Navigation: keep the class diagram close at hand!

  9. Conclusion… • Design • DRY: don’t repeat yourself • Convention, not configuration • Relationships are declared explicitly • Scaffolding: quick data entry (prototyping only) • Great development environment • has full debugging support; separate dev/prod db’s • Supports JavaScript/Ajax/etc. • Explore Ajax support next time

  10. Myths & Issues • Myth: slow sites, doesn’t scale • Supports many web servers • Many optimizations probably belong elsewhere • Technology improving • Myth: only for specific types of projects • Source: lots of simple examples out there • Can handle big problems • Don’t have to involve a database • See http://wiki.rubyonrails.org/rails/pages/RealWorldUsagePage1 • Issues • Active Records: should have Table classes • Ruby: run-time type checking requires lots of testing! • But has good built-in testing support! • Developers tempted to use all – pick level and stick to it

  11. Resources • Online tutorials • Classic text: Agile Web Development with Rails • Starting points: • http://guides.rubyonrails.org/getting_started.html • Beginning Rails: From Novice to Professional • In library, but based on Rails 1.x • Beginning Rails 3 • Available soon • More detail: The Rails Way

More Related