Intro to Rails | UCSB ACM

Introduction to web application development with Ruby on Rails

Transcript

1. Intro to Web Development with Ruby on Rails
2. Background?
3. What is Rails? • Open-source web framework "optimized for programmer happiness" * • Lets you quickly build and deploy dynamic web applications • Clearly defined conventions and philosophy lead to powerful and expressive code * This is a direct quote.
4. Ruby • A dynamic, interpreted language with a focus on simplicity and productivity • Combines aspects of object-oriented, functional, and imperative programming • Version 2.0.0 was just released on Sunday
5. Ruby
6. Rails is not a toy And 1000s more...
7. Rails 'Philosophy' • Convention over configuration ◦ All Rails projects have the same directory structure ◦ User model -> users table, user.rb, etc • Don't repeat yourself (DRY) ◦ Information in a single, unambiguous place ◦ Ex: layouts and partials
8. Full Stack Development • Rails works with all layers of a web application • Request routing • Database querying / schema management • Template rendering • etc...
9. Learn by Example • The classic Rails app: A blog • A trivial CRUD app - create, read, update, delete • How would we structure this app the Rails way?
10. MVC Architecture Model-View-Controller
11. Models • Represents your application domain objects ◦ Typically the nouns in an application ◦ A blog might have posts and users • Usually a 1-to-1 correspondence to a database table ◦ Ex: Post model implicitly tied to posts table • Home of validation and business logic ◦ "Fat model, skinny controller"
12. • Rails lets you declare a variety of associations between your models using a natural syntax • :post belongs_to :user • :customer has_many :orders • :supplier has_one :account Model Associations
13. • :post belongs_to :user ◦ Must also specify inverse: user has_many posts • Now you can write: user.posts # => [<Post 1>, <Post 2>] post.user # => <User 1> A one-to-many association
14. • Want to add tags to our blog posts (ex: 'ruby, programming, rails') • We could store a tag string on every post and then search through all posts for a match when looking for a tag • Insanely inefficient. How else to do it? Many-to-many associations
15. • post has_and_belongs_to_many tags • tag has_and_belongs_to_many posts • Need a join table between post_ids and tag_ids • Point is that after we declare the associations and create the table, Rails will take care of the heavy lifting with the foreign keys A many-to-many association
16. Post model skeleton
17. Views • The user interface of an application - what the user sees in their browser and interacts with • Scroll through a list of posts, or read a specific post • Links and forms send requests/data to the controller
18. Controllers • 'Glue' between models and views • Process requests from the browser, query the model for data, and pass that data to the views for presentation
19. Controllers • Mapping between controller actions and views # app/controllers/posts_controller.rb # app/views/posts/show.html.erb
20. Posts controller skeleton
21. Rails is RESTful • Representational state transfer • An architectural style developed by Roy Fielding • In Rails, resources provide automatic mapping between HTTP verbs and URLs to controller actions
22. A Rails Resource
23. What's in the box?
24. MAGIC • Dynamic finders User.find_by_email("something@gmail.com") • Resource paths <%= link_to "New Post", new_post_path %> • Lots of extensions to Ruby core ◦ "Is this method defined in Ruby or Rails???"
25. Database Adapters • ActiveRecord (Rails ORM) has adapters for working with most of the databases out there • Presents a single persistence API for the SQL variants: MySQL, PostgreSQL, Oracle, SQLite, ... • Can also plug in Redis, MongoDB, etc
26. Sass • CSS preprocessor • Makes CSS more sane with variables, nesting, mixins, and more • http://sass-lang.com/
27. CSS SCSS
28. CoffeeScript • A little language that compiles into JavaScript • Syntactic sugar enhances brevity/readability, and even adds a few features such as list comprehensions • http://coffeescript.org/
29. JavaScript CoffeeScript
30. Security • CSRF: One-liner to automatically generate security token for forms and compare them against a server-side secret • Mass-assignment attribute whitelisting • XSS: output is automatically escaped Recommended: The Rails Security Guide
31. Where to go from here • Ruby on Rails Tutorial by Michael Hartl • Agile Web Development with Rails • The Official Rails Guides
32. Questions?