What's new in Rails 2?

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 )
end
end

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.yml
my_blog:
name: "My awesome blog"
# posts.yml
first_post:
blog: my_blog
title: "First post!"

fixtures :all
Load 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 cookies
Prevents 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 layouts
Use 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 :posts
end
# Maps to PostsController
map.resources :posts

Semicolon is dead. Long live forward slash! 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 handlers
class 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_helpful
Now 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 %>

<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 %>

<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 action
assert_emails 1 do
post :signup , :name => "Bryan"
end
# Assert no emails are sent
post :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:
config/preinitializer.rb
config/environment.rb
config/environments/RAILS_ENV.rb
config/initializers/*.rb

Code annotations
Finds FIXME, TODO and OPTIMIZE comments.
$ rake notes
app/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. 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 :posts
end
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 upgrade
Upgrade to Rails 1.2.6.
Eliminate deprecation warnings.
Make sure all your tests pass.
Upgrade to Rails 2.0.1.
Run Mislav’s Rails 2 compatibility checker script. ( http://pastie.caboo.se/private/krcevozww61drdeza13e3a )
Make sure all your tests pass.

Questions? What’s new in Rails 2? Bryan Helmkamp http://brynary.com / / / /
http://www.flickr.com/photos/kaufman/81616562/
http://icanhascheezburger.com/2007/01/12/wait-ill-fix-it/
Photos used

http://www.informatik-student.de	306
http://railsfs.blogspot.com	35
http://www.slideshare.net	22
http://cntt.tv	19
http://www.dmitvn.com	3
http://peleqe2.forogratis.es	3
http://www.filescon.com	2
http://blog.maxschulze.com	1
http://maxschulze.tumblr.com	1
file://	1
http://www.rapidsharefast.com	1
http://www.sadavi.com.vn	1
http://funwithprogramming.blogspot.com	1
http://simplesideias.com.br	1
http://gmodules.com	1

What's new in Rails 2?

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