What’s new in Rails 2?Bryan Helmkamp

http://brynary.com/

“Look at all the things I’m NOT

doing.”–DHH during the “Creating a blog

in 15 minutes” screencast

Evolutionary, not revolutionary.

ActiveRecord

Numerical validation

•Gains the ability to specify comparisons.

•Examples:validates_numericality_of :salary, :greater_than => 49_000

validates_numericality_of :age, :less_than_or_equal => 99

validates_numericality_of :employees, :greater_than => 0

:allow_blank => true

Skips validation for empty strings and nil.

XML in, JSON out>> Post.new.from_xml({:title => "Hello!", :body => "text"}.to_xml)

=> #<Post id: nil, title: "Hello!", body: "text", created_at: nil, updated_at: nil>

>> Post.new(:title => "Hello!", :body => "text").to_json

=> "{"updated_at": null, "title": "Hello!", "body": "text", "created_at": null}"

Sexy migrations

create_table :posts do |t|

t.belongs_to :blog, :null => false

t.string :title, :subtitle

t.text :body

t.timestamps

end

Query cache•Very dumb. Checks SQL string

equality.

•Cleared by any INSERT/UPDATE/DELETE.

•Enabled per-action by default.

•Can be skipped if necessary:def self.uncached_newest uncached do find(:all, :order => :created_at) endend

Foxy Fixtures

Three main features

•Don’t specify the IDs for each record.

•Reference associated fixtures by name.

•Sets created_at and updated_at to Time.now automatically.

Foxy Fixtures example

# blogs.ymlmy_blog: name: "My awesome blog"

# posts.ymlfirst_post: blog: my_blog title: "First post!"

fixtures :allLoad all fixtures for all test cases.

(Recommended!)

ActionPack

Cookie sessions•Now the default session store.

•Stored in clear text, secured with a hash.

•Configure a secret in environment.rb:

Rails::Initializer.run do |config| config.action_controller.session = { :session_key => '_rails_app_session', :secret => 'e96a9......aef9111a' }end

HTTP-only cookiesPrevents access to cookies from JavaScript.

CSRF protection

•Enabled by default in application.rb

•Uses a token to verify requests are from the application, not a malicious site.

•Built-in to form_tag and friends.

Partial layoutsUse with partials:<% render :partial => "post", :layout => "window" %>

or with a block:<% render :layout => "window", :locals => { :name => "Recent" } do %>

<% for post in @recent_posts %>

<h2><%=h post.title %></h2>

<!-- ... -->

<% end %>

<% end %>

Route namespaces

map.namespace :admin do |admin| # Maps to Admin::PostsController admin.resources :postsend# Maps to PostsControllermap.resources :posts

Semicolon is dead.Long live forward

slash!

Association routing shortcuts

map.resources :blogs, :has_many => [:posts, :themes], :has_one => :owner

HTTP authentication

class PostsController < ApplicationController

USER_NAME, PASSWORD = "bryan", "secret"

before_filter :authenticate, :except => [ :index ]

...

private

def authenticate

authenticate_or_request_with_http_basic do |user_name, password|

user_name == USER_NAME && password == PASSWORD

end

end

end

Exception handlersclass ApplicationController < ActionController::Base

rescue_from User::NotAuthorized, :with => :deny_access

rescue_from 'MyAppError::Base' do |exception|

render :xml => exception.to_xml, :status => 500

end

protected

def deny_access

# ...

end

end

Asset caching

•Concatenates file contents.

•Only active in production mode.

•Examples:<%= stylesheet_link_tag "reset", "main", :cache => true %>

<%# Cache in public/javascripts/special.js %>

<%= javascript_include_tag "whiz", "bang", :cache => "special" %>

Asset servers

•Distributes request to four asset hosts.

•Speeds up page load time considerably.

•In production.rb:ActionController::Base.asset_host = "asset

%d.example.com"

AtomFeedHelper# index.atom.builder:

atom_feed do |feed|

feed.title("Bryan's Bytes")

feed.updated((@posts.first.created_at))

for post in @posts

feed.entry(post) do |entry|

entry.title(post.title)

entry.content(post.body, :type => 'html')

entry.author do |author|

author.name("NYC.rb")

end

end

end

end

Multiview

•Template filename changes:

filename.format.renderer

•Examples:

show.csv.erb

edit.html.haml

index.atom.builder

simply_helpfulNow in core... but you should’ve been using it

already.

dom_class and dom_id

•dom_class(@person) => "person"

•dom_class(Person) => "person"

•dom_class(@person, :edit) => "edit_person"

•dom_id(@person) => "person_1234"

•dom_id(Person.new) => "new_person"

div_for/content_tag_for<% div_for @person do %> <!-- ... --><% end %>

<!-- Becomes --><div class="person" id="person_42"> <!-- ... --></div>

url_for for models

•url_for(@post) works like post_path(@post).

•url_for(Post.new) works like new_post_path.

•Works with link_to, redirect_to, etc.

render :partial for AR

• render :partial => @post works like render :partial => "post", :object => @post

• render :partial => @posts works like render :partial => "post", :collection => @posts

form_for•Determines form action based on

the record. (e.g. post_path or new_post_path)

•New records use :method => :post

•Existing records use :method => :put

•Automatically adds a HTML class and ID

form_for example

<% form_for @person do |f| %>

<%= f.text_field :name %>

<% end %>

<!-- Becomes -->

<form action="/people" method="post" class="person" id="new_person">

<input type="text" name="person[name]" id="person_name" />

</form>

Extra Goodies

Debugging

Getting started

•sudo gem install -y ruby-debug

•Call the method “debugger” in your code

•script/server --debugger

Debugger commands

• irb – Drop into an irb session

• list – List the code surround the breakpoint

•p/pp – Print results of an expression

•up – Move one frame higher

• cont – Resume execution

•next/step – Execute one line at a time.

•where – Display the current stack

Live demo

assert_emails

# Assert one email is sent during actionassert_emails 1 do post :signup, :name => "Bryan"end

# Assert no emails are sentpost :signup, :name => ""assert_no_emails

Hash filtering

•Hash#except is the inverse of Hash#slice.

•Example:

>> {:foo => 1, :bar => 2}.except(:bar, :baz)

=> {:foo=>1}

Database Rake tasks

•rake db:create and db:create:all

•rake db:drop and db:drop:all

•rake db:reset

•rake db:rollback (defaults to STEP=1)

•rake db:version

List routes with Rake

$ rake routes

posts GET /posts {:controller=>"posts", :action=>"index"}

formatted_posts GET /posts.:format {:controller=>"posts", :action=>"index"}

POST /posts {:controller=>"posts", :action=>"create"}

POST /posts.:format {:controller=>"posts", :action=>"create"}

new_post GET /posts/new {:controller=>"posts", :action=>"new"}

formatted_new_post GET /posts/new.:format {:controller=>"posts", :action=>"new"}

edit_post GET /posts/:id/edit {:controller=>"posts", :action=>"edit"}

formatted_edit_post GET /posts/:id/edit.:format {:controller=>"posts", :action=>"edit"}

post GET /posts/:id {:controller=>"posts", :action=>"show"}

formatted_post GET /posts/:id.:format {:controller=>"posts", :action=>"show"}

PUT /posts/:id {:controller=>"posts", :action=>"update"}

PUT /posts/:id.:format {:controller=>"posts", :action=>"update"}

DELETE /posts/:id {:controller=>"posts", :action=>"destroy"}

DELETE /posts/:id.:format {:controller=>"posts", :action=>"destroy"}

/:controller/:action/:id

/:controller/:action/:id.:format

Initializer hooks

Rails load order:

1.config/preinitializer.rb

2.config/environment.rb

3.config/environments/RAILS_ENV.rb

4.config/initializers/*.rb

Code annotations

Finds FIXME, TODO and OPTIMIZE comments.

$ rake notesapp/models/post.rb: * [ 2] [TODO] : Add support for themes

app/views/layouts/application.rhtml: * [ 1] [FIXME] Will break with less than three posts

Request profiler

•sudo gem install -y ruby-prof

•Example:$ cat login_session.rb

get_with_redirect '/'

post_with_redirect '/sessions', :password => 'NYC.rb!'

$ ./script/performance/request -n 10 login_session.rb

Losing weight

ActionWebService is out.Use ActiveResource for

REST.

acts_as_* behaviors

script/plugin install http://svn.rubyonrails.org/rails/plugins/acts_as_list/

script/plugin install

http://svn.rubyonrails.org/rails/plugins/acts_as_nested_set/

script/plugin install

http://svn.rubyonrails.org/rails/plugins/acts_as_tree/

Controller variables

•Don’t use @params, @session, @flash, @request or @env.

•Just drop the “@” and use the methods.

ActiveRecord finders

•Post.find_all becomes Post.find(:all).

•Post.find_first becomes Post.find(:first).

Components

•Interesting feature, but too slow.

•Try refactoring to partials and filters...

•...or grab Sebastian Delmont’s plugin:

http://dev.notso.net/svn/rails/plugins/embedded_actions/trunk/

Renamed routes

•Nested resources now use the parent name as a prefix.

•Example:map.resources :blogs do |blog| blog.resources :postsend•post_path becomes blog_post_path, etc.

Pagination

Switch to will_paginate (recommended).

http://errtheblog.com/posts/56-im-paginating-again

Or install the classic_pagination plugin:

script/plugin install svn://errtheblog.com/svn/plugins/classic_pagination

Database adapters

Adapters except SQLite, MySQL and PostgreSQL were removed from Rails core.

sudo gem install activerecord-oracle-adapter

Form helpers

•start_form_tag and end_form_tag are gone.

•Switch to the form_tag block syntax.

•Use form_for when possible.

form_tag example

<%= start_form_tag posts_path %> <%= text_field :post, :title %><%= end_form_tag %>

becomes <% form_tag posts_path do %> <%= text_field :post, :title %> <% end %>

AJAX view helpers

Autocomplete and in-place editing moved to plugins.script/plugin install http://svn.rubyonrails.org/rails/plugins/auto_complete/

script/plugin install http://svn.rubyonrails.org/rails/plugins/in_place_editing/

“Use the Source, Luke.”

How to upgrade1.Upgrade to Rails 1.2.6.

2.Eliminate deprecation warnings.

3.Make sure all your tests pass.

4.Upgrade to Rails 2.0.1.

5.Run Mislav’s Rails 2 compatibility checker script. (http://pastie.caboo.se/private/krcevozww61drdeza13e3a)

6.Make sure all your tests pass.

Questions?What’s new in

Rails 2?Bryan Helmkamp

http://brynary.com/

Photos used• http://www.flickr.com/photos/kaufman/81616562/

• http://icanhascheezburger.com/2007/01/12/wait-ill-fix-it/