What's new and great in Rails 3 - Matt Gauger - Milwaukee Ruby Users Group December 2010

What’s new and great inRails 3

Don’t worry! All the links Text shown will bepresented at the end of the slides and on my blog.

There’s a lot to talk about, so

This is a longpresentation

I wanted to do something different thanlist the changes in Rails 3

Allow me to introduce you to someone.

This is Robin

“Robin would very much like to be akick-ass web developer, but has a hardtime keeping up with the buzzwords.” -- Flickr description

He’s a webdeveloper

He uses Rails 2.3 at his job,

where they make state-of-the-art TODO list web applications (and ﬁght crime)

His boss

Batman

Wants the team to use Rails 3.

Because he heard itis the new hotness.

Batman tries to stay hip with the “web stuff”

Robin is already fairly familiar with Rails

In this case, he’s going to be starting from scratch

While it is possible to upgrade from Rails 2.x toRails 3, we’re not going to.

This is merely a learningexercise, so we’re skippingthe BDD/TDD for now, too.

Robin keeps up with a few Rails blogs,

And he’s read that rvmis what everyone is using

rvm is a way to install and use different versions ofRuby on the same machine

Robin uses Homebrewon his Mac, so he types:

$ brew install rvm

Sidenote:My recommendation would be to start with Cinderella if you’re on a Mac

What comes with Cinderella?

• mysql, postgres, redis, memcached andmongodb•ruby (1.8.7) with rails and sinatra viarvm gemsets. (& install Ruby 1.9 with rvm)•python (2.7) with pip.•node.js (0.2.0) with npm.•erlang (R13B04) environment.... and brew, and probably a lot more bynow.

With rvm, Robin can do this:

$ rvm install 1.9.2$ rvm use 1.9.2

$ rvm listrvm rubies ruby-1.8.7-p248 [ x86_64 ]=> ruby-1.9.2-p0 [ x86_64 ]

$ ruby -vruby 1.9.2p0 (2010-08-18 revision29036) [x86_64-darwin10.4.1]

So now Robin isrolling on Ruby 1.9.2

Next, he needs a gemset

A gemset is a collection ofgems, in this case that we’re associating with a project

Robin knows this comes in later, when he startsusing bundler in his app

$ rvm gemset create totodo$ rvm ruby-1.9.2-p0@totodo

Now any gems he installs will be on Ruby 1.9.2

And more importantly,will be kept with his app.

Robin installs Rails 3.0.3

$ gem install rails -v 3.0.3

And the Heroku gem

$ gem install heroku

He creates a new app called totodo (it’s a todo list!)

# Create a new Rails 3 app:$ rails new totodo$ cd totodo/

And grabs gems thatRails needs with Bundler

# Use Bundler to install gems:$ bundle install

Let’s look at Bundler

In Rails 2, Robinwould have to do this:

# Edit environment.rb:config.gem "haml"config.gem "sass"# Then do$ rake gems:install

In Rails 3 with Bundler:

# Edit the Gemfile:source "http://rubygems.org"gem "haml"gem "sass"# Then run:$ bundle install

We can also usegroups for gems:

# Gemfile:source "http://rubygems.org"gem "haml"gem "sass"group :test,:development do gem "webrat" gem "rspec"end# Then go run:$ bundle

Now webrat and rspec will be installed and used, butonly in the environments listed

Moving on, we setup git and heroku

# Set up git repo:$ git init .$ git add *$ git commit -m “Initial commit ofbare Rails 3 project.”# Create a new Heroku app:$ heroku create$ git push heroku master

Robin is all set to develop

He’s is looking at the ﬁles in his newly created project,

and noticing some differences

conﬁg/application.rb(replaces conﬁg/environment.rb)

require File.expand_path(../boot, __FILE__)require rails/all# If you have a Gemfile, require the gems listed there, including any gems# youve limited to :test, :development, or :production.Bundler.require(:default, Rails.env) if defined?(Bundler)module Totodo class Application < Rails::Application # [With a lot of comments cleaned up] # Configure generators values. config.generators do |g| g.orm :active_record g.template_engine :haml g.test_framework :rspec, :fixture => true end # Configure the default encoding used in templates for Ruby 1.9. config.encoding = "utf-8" # Configure sensitive parameters which will be filtered from the log file. config.filter_parameters += [:password] endend

The important bit is

# Robin is going to use haml and rspec:# Configure generators values.config.generators do |g| g.orm :active_record g.template_engine :haml g.test_framework :rspecend

Robin needs a data model for what he’s storing

Which is a TODO list item

What makes up aTODO list item?

•ID•Title (Text)•Due Date (Datetime)•Is it done? (Boolean)

Robin wants to use $ script/generatewhich he comfortable with

But there isn’t ascript/generate in Rails 3

# Inside his totodo project folder:$ ls -al script/total 8drwxr-xr-x 3 robin staff 102 Dec 20 01:53 .drwxr-xr-x 21 robin staff 714 Dec 20 01:55 ..-rwxr-xr-x 1 robin staff 295 Dec 20 01:53 rails

Instead, everything goes through the rails script

# Remember doing these commands?$ script/generate something$ script/server$ script/console

# Replaced with:$ rails generate something$ rails g something #shorter form$ rails server$ rails s # shorter form$ rails console

What Robin wants is a scaffold

Again, he’s just learning Rails 3 here, so a scaffold will be ﬁne.

$ rails generate scaffold Todo title:string due_date:datetime done:boolean

$ rails generate scaffold Todo title:string due_date:datetime done:boolean invoke active_record create db/migrate/20101220080933_create_todos.rb create app/models/todo.rb invoke test_unit create test/unit/todo_test.rb create test/fixtures/todos.yml route resources :todos invoke scaffold_controller create app/controllers/todos_controller.rb invoke erb create app/views/todos create app/views/todos/index.html.erb create app/views/todos/edit.html.erb create app/views/todos/show.html.erb create app/views/todos/new.html.erb create app/views/todos/_form.html.erb[and lots more output than this]

That’s a lot ofgenerated ﬁles

Robin wants to knowwhether migrations are different in Rails 3

So he looks in

db/migrate/20101220080933_create_todos.rb

class CreateTodos < ActiveRecord::Migration def self.up create_table :todos do |t| t.string :title t.datetime :due_date t.boolean :done t.timestamps end end def self.down drop_table :todos endend

That’s very similar towhat Robin is used to.

Robin runs the migration.

$ rake db:migrate(in /Users/robin/Projects/totodo)== CreateTodos: migrating ==================================-- create_table(:todos) -> 0.0019s== CreateTodos: migrated (0.0020s) =========================

Now, Robin wants to hook upthe routes to his new controller

He’s read that routes in Rails 3 are different,

but he hasn’t seen them yet

He’s pleased to ﬁndthat they’re simple:

# in config/routes.rb our scaffold placed:Totodo::Application.routes.draw do resources :todosend

Robin deletes thepublic/index.html ﬁle and maps the root path:

Totodo::Application.routes.draw do root :to => todos#index resources :todosend

And runs his dev server withthat nifty `rails s` command

Robin wants validations on his model

A ToDo list itemshould have a title

The syntax haschanged a little

class Todo < ActiveRecord::Base validates :title, :presence => trueend

Robin has a very,very basic app started

And a long way to go with Rails 3

Robin has a little bit oftime during his lunch break

So he reads up on the Merb project

2006:The Merb project was started

At its start, Merb justserves ERb templates from Mongrel

Merb focuses on essentials

Componentmodularity

Extensible APIs

ORM/JS framework agnostic

December 2008:The Rails team announcesRoR and Merb will merge

Rails 3 is the result ofmerging Merb and RoR

And represents asigniﬁcant rewrite of most of Rails

Robin has stumbledonto a blog post by

Yehuda Katz

Summarizing theMerb+RoR merger back in 2008

Rails will become more modular

Rails will have better performance

Rails 3 will have a deﬁned API, and atest suite for that API

Rails will allow things like DataMapper or Sequel to be ﬁrst-class ORMs

Rails 3 will continue to embrace Rack

Reinvigorated, Robinjumps back into dev

As he begins to modifyhis controller, he runs into

(ActiveRelation)

Arel provides anSQL abstraction

Using relational algebra

Old and busted:

@users = User.find(:all, :conditions => {:approved => true})

New Hotness:

@users = User.where(:approved => true)

The Rails 2.x-style .ﬁnd() method queries the DBimmediately and returns an array

The Arel-style .where() method returns anActiveRecord::Relation

What can we do with an ActiveRelation?

Add additionalparameters to the query

@users = User.where(:approved => true)# If a params[:order] was passed in,# add that condition to the query:@users = @users.order(params[:order])@users.each do |u| ...end

@users = User.where(:approved => true)# If a params[:order] was passed in,# add that condition to the query:@users = @users.order(params[:order])@users.each do |u| # Query runs here! ...end

We can even chain the last page of code together:

User.where(:approved => true).order(params[:order])

Rails 2:named_scope method

Rails 3:scope keyword

# Rails 2:class User < ActiveRecord::Base named_scope :approved, :conditions => {:approved => true}end# Rails 3:class User < ActiveRecord::Base scope :approved, where(:approved => true)end

There’s much, much more to Arel. Read the documentation.

Next up, Robin discovers that he can match any Rack app to a route

Totodo::Application.routes do match "/home", :to => HomeAppend

In fact, this is a lot likethe routes we saw earlier

Totodo::Application.routes.draw do root :to => todos#index match "/home", :to => HomeAppend

todos#indexhere is really a full ﬂedgedRack application, too.

Routes are namespaced inside your app.

# Instead of:ActionController::Routing::Routes.draw do |map| map.resources :todosend# You do:Totodo::Application.routes do resources :todosend

The i18n gem brings in better i18n support, but Robin isn’tgoing to get into that right now.

How has ourController changed?

A simpliﬁed version of what our scaffold created would be:

class TodosController < ApplicationController respond_to :html, :xml, :js # GET /todos # GET /todos.xml def index respond_with(@todos = Todo.all) endend

As you can see, respond_to deﬁnes the formats the Controller responds to

And responds_with isthe data to send back

Our scaffold has alreadycreated the methods for our Todos controller

Robin pushes the app to Heroku

$ git push heroku master[... lots of output ...]-----> Launching... done http://deep-mountain-360.heroku.com/deployed to HerokuTo git@heroku.com:deep-mountain-360.git * [new branch] master -> master

Where can Robin go to learn more?

Robin can work through theRails Tutorial book for Rails 3: http://railstutorial.org/book

Which is a great resource. Highly recommended!

Robin is now equipped to ﬁght crime, writeTODO lists, and learn more about Rails 3!

His boss wants to give him a little congrats

“POW”

Thank you!

See me after for free Github stickers :-)

Media used:http://www.flickr.com/photos/geirarne/43102913/(CC Attribution-NonCommercial-ShareAlike 2.0)http://www.flickr.com/photos/redraspus/2883658175(CC Attribution-NonCommercial-ShareAlike 2.0)http://www.flickr.com/photos/patolucas/2862975260/(CC Attribution-ShareAlike 2.0 Generic)

Links:https://github.com/atmos/cinderellahttp://rvm.beginrescueend.com/http://yehudakatz.com/2008/12/23/rails-and-merb-merge/http://railsforzombies.orghttp://railstutorial.org/bookhttp://rubyonrails.org/screencasts/rails3/https://github.com/brynary/arel

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What's new and great in Rails 3 - Matt Gauger - Milwaukee Ruby Users Group December 2010

by Matt Gauger on Dec 30, 2010

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What’s new and great in Rails 3 - Matt Gauger - Milwaukee Ruby Users Group December 2010 — Presentation Transcript