Ruby on Rails Cheat Sheet Collectors Edition

This Ruby on Rails cheat sheet is a reference guide for that will be continuosly updated and improved as new features are added to rails and new cheat sheet tips are added to the guide. It is a collection from the one of the very best guides, apis and source snippets that are concise that i’ve found. I’ve fixed errors and added highlighting to it and it is a mirror of the one found on nanorails site plus my own changes. New updates will be posted to this post under Recent Updates.

Recent Updates

* Oct 5 - ActionMailer and Testing added
* Oct 5 - Printable Cheatsheet Added!
* Oct 5 - Presentations added
* Oct 4 - Initial Cheat Sheet Posted
* Fixed for IE (h3 headers)

Ruby on Rails 1.16 - Edge Reference

Create a rails application

$ rails app_name



-d, –database=xxx specify which database to use (mysql oracle postgresql sqlite2 sqlite3 ), defaults to mysql
-r, –ruby-path= specify the path to ruby, if not set, the scripts use env to find ruby
-f, –freeze freezes Rails into the vendor/rails directory

API Documentation

$ gem_server

Open a web browser with the address localhost:8808


is the make of ruby - the R uby m AKE. Rails defines a number of tasks to help you:

rake db:fixtures:load          # Load fixtures into the current environment's database. 
                               # Load specific fixtures using FIXTURES=x,y
rake db:migrate                # Migrate the database through scripts in db/migrate. Target 
                               # specific version with VERSION=x
rake db:schema:dump            # Create a db/schema.rb file that can be portably used against 
                               # any DB supported by AR
rake db:schema:load            # Load a schema.rb file into the database
rake db:sessions:clear         # Clear the sessions table
rake db:sessions:create        # Creates a sessions table for use with 
                               # CGI::Session::ActiveRecordStore
rake db:structure:dump         # Dump the database structure to a SQL file
rake db:test:clone             # Recreate the test database from the current environment's 
                               # database schema
rake db:test:clone_structure   # Recreate the test databases from the development structure
rake db:test:prepare           # Prepare the test database and load the schema
rake db:test:purge             # Empty the test database

rake doc:app                   # Build the app HTML Files
rake doc:clobber_app           # Remove rdoc products
rake doc:clobber_plugins       # Remove plugin documentation
rake doc:clobber_rails         # Remove rdoc products
rake doc:plugins               # Generate documation for all installed plugins
rake doc:rails                 # Build the rails HTML Files
rake doc:reapp                 # Force a rebuild of the RDOC files
rake doc:rerails               # Force a rebuild of the RDOC files

rake log:clear                 # Truncates all *.log files in log/ to zero bytes

rake rails:freeze:edge         # Lock this application to latest Edge Rails. Lock a specific 
                               # revision with REVISION=X
rake rails:freeze:gems         # Lock this application to the current gems (by unpacking them 
                               # into vendor/rails)
rake rails:unfreeze            # Unlock this application from freeze of gems or edge and return 
                               # to a fluid use of system gems
rake rails:update              # Update both scripts and public/javascripts from Rails
rake rails:update:javascripts  # Update your javascripts from your current rails install
rake rails:update:scripts      # Add new scripts to the application script/ directory

rake stats                     # Report code statistics (KLOCs, etc) from the application

rake test                      # Test all units and functionals
rake test:functionals          # Run tests for functionalsdb:test:prepare
rake test:integration          # Run tests for integrationdb:test:prepare
rake test:plugins              # Run tests for pluginsenvironment
rake test:recent               # Run tests for recentdb:test:prepare
rake test:uncommitted          # Run tests for uncommitteddb:test:prepare
rake test:units                # Run tests for unitsdb:test:prepare

rake tmp:cache:clear           # Clears all files and directories in tmp/cache
rake tmp:clear                 # Clear session, cache, and socket files from tmp/
rake tmp:create                # Creates tmp directories for sessions, cache, and sockets
rake tmp:sessions:clear        # Clears all files in tmp/sessions
rake tmp:sockets:clear         # Clears all ruby_sess.* files in tmp/sessions


script/about            # Information about environenment
script/breakpointer     # starts the breakpoint server
script/console          # interactive Rails Console
script/destroy          # deletes files created by generators
script/generate         # -> generators
script/plugin           # -> Plugins
script/runner           # executes a task in the rails context
script/server           # launches the development server
                        # http://localhost:3000

script/performance/profiler     # profile an expenive method
script/performance/benchmarker  # benchmark different methods



ruby script/generate model ModellName
ruby script/generate controller ListController show edit
ruby script/generate scaffold ModelName ControllerName 
ruby script/generate migration AddNewTable
ruby script/generate plugin PluginName
ruby script/generate mailer Notification lost_password signup
ruby script/generate web_service ServiceName api_one api_two
ruby script/generate integration_test TestName
ruby script/generate session_migration

Rails Generator Options

-p, --pretend                    Run but do not make any changes.
-f, --force                      Overwrite files that already exist.
-s, --skip                       Skip files that already exist.
-q, --quiet                      Suppress normal output.
-t, --backtrace                  Debugging: show backtrace on errors.
-h, --help                       Show this help message.
-c, --svn                        Modify files with subversion. (Note: svn must be in path)

Rails Plugins

script/plugin discover          # discover plugin repositories
script/plugin list              # list all available plugins
script/plugin install where     # install the „where' plugin
script/plugin install -x where  # install where plugin as SVN external
script/plugin install
script/plugin update            # update installed plugins
script/plugin source            # add a source repository
script/plugin unsource          # removes a source repository
script/plugin sources           # lists source repositories

A searchable directory of plugins can be found at AgileDevelopment.

Testing - Functional and Unit Tests

def test_signup_mail
  MyMailer.deliver_signup_mail("", "Joe", "your new account", 
  assert !ActionMailer::Base.deliveries.empty?

  sent = ActionMailer::Base.deliveries.first
  assert_equal '',
  assert_equal "your new account", sent.subject
  assert_equal "", sent.from.first
  assert sent.body =~ /^some more stuff/


Model Relations

There are four ways of associating models. has_one, has_many, belongs_to and has_and_belongs_to_many

Model Associations

def Order < ActiveRecord::Base
  has_many :line_items
  belongs_to :customer   # there's a column "customer_id" in the db table

def LineItem < ActiveRecord::Base
  belongs_to :order # there's a column "order_id" in the db table

def Customer < ActiveRecord::Base
  has_many :orders
  has_one :address

def Address < ActiveRecord::Base
  belongs_to :customer

belongs_to  :some_model,
        :class_name  => 'MyClass',      # specifies other class name
        :foreign_key => 'my_real_id',   # and primary key 
        :conditions  => 'column = 0'    # only finds when this condition met 

has_one :some_model, 
        # as belongs_to and additionally:
        :dependent   => :destroy        # deletes associated object
        :order       => 'name ASC'      # SQL fragment for sorting

has_many :some_model
        # as has_one and additionally:
        :dependent => :destroy          # deletes all dependent data
                                        # calling each objects destroy
        :dependent => :delete_all       # deletes all dependent data
                                        # without calling the destroy methods
        :dependent => :nullify          # set association to null, not 
                                        # destroying objects
        :group => 'name'                # adds GROUP BY fragment
        :finder_sql => 'select ....'    # instead of the Rails finders
        :counter_sql => 'select ...'    # instead of the Rails counters

Habtm (Has and Belongs to Many)

def Category < ActiveRecord::Base 
  has_and_belongs_to_many :products
def Product < ActiveRecord::Base
  has_and_belongs_to_many :categories  

Table categories_products with category_id and product_id (without id column) Association Join Models

Through Model

class Author < ActiveRecord::Base
  has_many :authorships
  has_many :books, :through => :authorships

class Authorship < ActiveRecord::Base
  belongs_to :author
  belongs_to :book

class Book < ActiveRecord::Base
  has_one :authorship

@author = Author.find :first
@author.authorships.collect { |a| } # selects all books that the author's 
                                           # authorships belong to.
@author.books                              # selects all books by using the Authorship
                                           # join model

Also works through has_many associations:

class Firm < ActiveRecord::Base
  has_many   :clients
  has_many   :invoices, :through => :clients
  has_many   :paid_invoices, :through => :clients, :source => :invoice

class Client < ActiveRecord::Base
  belongs_to :firm
  has_many   :invoices

class Invoice < ActiveRecord::Base
  belongs_to :client

@firm = Firm.find :first
@firm.clients.collect { |c| c.invoices }.flatten # select all invoices for all clients
                                                 # of the firm
@firm.invoices                                   # selects all invoices by going through
                                                 # the Client join model.

Rails Validations

validates_presence_of :firstname, :lastname     # must be filled out

validates_length_of :password,
                    :minimum => 8           # more than 8 characters
                    :maximum => 16          # shorter than 16 characters
                    :in => 8..16            # between 8 and 16 characters
                    :too_short => 'way too short'    
                    :too_long => 'way to long'

validates_acceptance_of :eula               # Must accept a condition
                        :accept => 'Y'      # default: 1 (ideal for a checkbox)

validates_confirmation_of :password     
# the fields password and password_confirmation must match

validates_uniqueness_of :user_name              # user_name has to be unique
                        :scope => 'account_id'  # Condition: 
                                                # account_id = user.account_id

validates_format_of :email          # field must match a regular expression
                    :with => /^([^@\s]+)@((?:[-a-z0-9]+.)+[a-z]{2,})$/i

validates_numericality_of   :value                  # value is numeric
                            :only_integer => true   
                            :allow_nil => true      

validates_inclusion_in  :gender,    # value is in enumeration
                        :in => %w( m, f )

validates_exclusion_of  :age            # value is not in Enumeration
                        :in => 13..19   # don't want any teenagers

validates_associated :relation  
# validates that the associated object is valid

Options for all validations above

:message => 'my own errormessage'   # eigene Fehlermeldung
:on      => :create                 # or :update (validates only then)
:if      => ...                     # call method oder Proc


Person.average :age
Person.minimum :age
Person.maximum :age
Person.sum :salary, :group => :last_name

Find Method

find(42)        # object with ID 42
find([37, 42])  # Array with the objects with id 37, 42
find :all
find :first, 
     :conditions => [ "name = ?", "Hans" ]   # finds the first record with 
                                             # the matching condition

more parameters for find

:order => 'name DESC'       # sql fragment for sorting
:offset => 20               # starts with entry 20
:limit => 10                # only return 10 objects
:group => 'name'            # sql fragment GROUP BY
:joins => 'LEFT JOIN ...'   # additional LEFT JOIN (rarely used)
:include => [:account, :friends]    # LEFT OUTER JOIN with these model
:include => { :groups => { :members=> { :favorites } } } 
:select => [:name, :adress]     # instead of SELECT * FROM
:readonly => true               # objects are write protected


Developer.with_scope(:find => { :conditions => "salary > 10000", :limit => 10 }) do
  Developer.find(:all)     # => SELECT * FROM developers WHERE (salary > 10000) LIMIT 10

  # inner rule is used. (all previous parameters are ignored)
  Developer.with_exclusive_scope(:find => { :conditions => "name = 'Jamis'" }) do
    Developer.find(:all)   # => SELECT * FROM developers WHERE (name = 'Jamis')

  # parameters are merged
  Developer.with_scope(:find => { :conditions => "name = 'Jamis'" }) do
    Developer.find(:all)   # => SELECT * FROM developers WHERE 
                           # (( salary > 10000 ) AND ( name = 'Jamis' )) LIMIT 10

for more details and examples, see: * *


During the life cycle of an active record object, you can hook into 9 events:

* (-) save
    * (-) valid?
    * (1) before_validation
    * (2) before_validation_on_create
    * (-) validate
    * (-) validate_on_create
    * (4) after_validation
    * (5) after_validation_on_create
    * (6) before_save
    * (7) before_create
    * (-) create
    * (8) after_create
    * (9) after_save

AR Examples

class Subscription < ActiveRecord::Base
  before_create :record_signup
  def record_signup
    self.signed_up_on =

class Firm < ActiveRecord::Base
  # Destroys the associated clients and people when the firm is destroyed
  before_destroy { |record| Person.destroy_all "firm_id = #{}"   }
  before_destroy { |record| Client.destroy_all "client_of = #{}" }


The Observer classes let’s you extract the functionality of the callbacks:

class CommentObserver < ActiveRecord::Observer
  def after_save(comment)
    Notifications.deliver_comment("", "New comment was posted", comment)

Store observers in app/model/model_observer.rb Enable observer by putting this in config/environment.rb

config.active_record.observers = :comment_observer, :signup_observer

Rails Migration

ruby sript/generate migration AddTables Creates a file db/migrations/001_add_tables. The methods ‘up’ and ‘down’ change the db schema

def self.up     # brings db schema to the next version 
  create_table :table, :force => true do |t|
    t.column :name, :string
    t.column :age, :integer, { :default => 42 }
    t.column :description, :text
    # :string, :text, :integer, :float, :datetime, :timestamp, :time, :date, 
    # :binary, :boolean
  add_column :table, :column, :type
  rename_column :table, :old_name, :new_name 
  change_column :table, :column, :new_type
  execute "SQL Statement"
  add_index :table, :column, :unique => true, :name => 'some_name'
  add_index :table, [ :column1, :column2 ]

def self.down   # rollbacks changes
  rename_column :table, :new_name, :old_name
  remove_column :table, :column
  drop_table :table
  remove_index :table, :column

To execute the migration


rake db:migrate
rake db:migrate VERSION=14
rake db:migrate RAILS_ENV=production

Unit Test

rake test:units The following assertions are available:

assert_kind_of Class, @var  # same class
assert @var                 # not nil
assert_equal 1,       # equality
assert_raise(ActiveRecord::RecordNotFound) { Product.find( ) }


Controller methods

Each public method in a controller is callable by the (standard) URL scheme /controller/action

class WorldController < ApplicationController
def hello
  render :text => 'Hello world'

Parameters are stored in the params hash

id = params[:id]     # 1
foo = params[:foo]   # bar

Instance variables defined in the the controllers methods

are available to the corresponding view templates:

def show
  @person = Person.find( params[:id])

Distinguish the type of response accepted

def index
  @posts = Post.find :all

  respond_to do |type|
    type.html # using defaults, which will render weblog/index.rhtml
    type.xml  { render :action => "index.rxml" }
    type.js   { render :action => "index.rjs" }

Render in Rails

Usually the view template with the same name as the controller method is used to render the results

Render Action

render :action => 'some_action'   # the default. Does not need to be specified
                                   # in a controller method called "some_action"
render :action => 'another_action', :layout => false
render :action => 'some_action', :layout => 'another_layout'

Render Partials

Partials are stored in files called '_subformname' ( _error, _subform, _listitem)

render :partial => 'subform'
render :partial => 'error', :status => 500
render :partial => 'subform', :locals => { :variable => @other_variable }
render :partial => 'listitem', :collection => @list
render :partial => 'listitem', :collection => @list, :spacer_template => 'list_divider'

Render Template

Like rendering an action, but finds the template based on the template root (app/views)

render :template => 'weblog/show'  # renders app/views/weblog/show

Render File

render :file => '/path/to/some/file.rhtml'
render :file => '/path/to/some/filenotfound.rhtml', status => 404, :layout => true


render :text => "Hello World"
render :text => "This is an error", :status => 500
render :text => "Let's use a layout", :layout => true
render :text => 'Specific layout', :layout => 'special'

Render Inline Template

Uses ERb to render the ‘miniature’ template

render :inline => "<%= 'hello , ' * 3 + 'again' %>"
render :inline => "<%= 'hello ' + name %>", :locals => { :name => "david" }

Render Nothing

render :nothing
render :nothing, :status => 403    # forbidden

Rails RJS Rendering

def refresh
  render :update do |page|
    page.replace_html  'user_list', :partial => 'user', :collection => @users
    page.visual_effect :highlight, 'user_list'

Change the content-type

render :action => "atom.rxml", :content_type => "application/atom+xml"

Rails URL Routing / Mapping

In config/routes.rb

map.connect '', :controller => 'posts', :action => 'list' # default
map.connect ':action/:controller/:id'
map.connect 'tasks/:year/:month', :controller => 'tasks', 
                                  :action => 'by_date',
                                  :month => nil, :year => nil,
                                  :requirements => {:year => /\d{4}/, 
                                                    :month => /\d{1,2}/ }

Rails Filters

Filters can change a request before or after the controller. They can for example be used for authentication, encryption or compression.

before_filter :login_required, :except => [ :login ]
before_filter :autenticate, :only => [ :edit, :delete ]
after_filter :compress

It’s also possible to use a Proc for a really small filter action:

before_filter { |controller| false if controller.params["stop_action"] }

Change the order of your filters by using prepend_before_filter and prepend_after_filter (like prepend_before_filter :some_filter which will put the some_filter at the beginning of the filter chain) If you define a filter in a super class, you can skip it in the subclass:

skip_before_filter :some_filter
skip_after_filter :some_filter

Set default characters for RJS to UTF-8

In application.rb put:

before_filter :set_charset

  # Sets default character set to UTF-8
  def set_charset
    if request.xhr?
      @headers["Content-Type"] = "text/javascript; charset=utf-8"
      @headers["Content-Type"] = "text/html; charset=utf-8"

Session / Flash

To save data across multiple requests, you can use either the session or the flash hashes. A flash stores a value (normally text) until the next request, while a session stores data during the complete session.

session[:user] = @user
flash[:message] = "Data was saved successfully"

<%= link_to "login", :action => 'login' unless session[:user] %>
<% if flash[:message] %>
<div><%= h flash[:message] %></div>
<% end %>

Session management

* Also see Session Expiration It’s possible to turn off session management:

session :off                        # turn session managment off                        
session :off, :only => :action      # only for this :action
session :off, :except => :action    # except for this action
session :only => :foo,              # only for :foo when doing HTTPS
        :session_secure => true 
session :off, :only => :foo,        # off for foo, if uses as Web Service
        :if => { |req| req.parameters[:ws] }


Rails Setting Cookies

cookies[:user_name] = "david" # => Will set a simple session cookie
cookies[:login] = { :value => "XJ-122", :expires => + 3600} 
    # => Will set a cookie that expires in 1 hour

Reading Cookies

cookies[:user_name] # => "david"
cookies.size         # => 2

Deleting Cookies

cookies.delete :user_name

All the option symbols for setting cookies are:

* value - the cookie’s value or list of values (as an array).
    * path - the path for which this cookie applies. Defaults to the root of the application.
    * domain - the domain for which this cookie applies.
    * expires - the time at which this cookie expires, as a +Time+ object.
    * secure - whether this cookie is a secure cookie or not (default to false). Secure cookies are only transmitted to HTTPS servers.

Rails Views

View Templates

All view templates are stored in app/views/controllername. The extension determines what kind of template format is used:

* rhtml Ruby HTML (using ERB)
    * rxml Ruby XML (using Builder)
    * rjs Ruby JavaScript

All instance variables of the controller are available to the view. In addition, the following special objects can be accessed:

* headers The Headers of the outgoing response
    * request The incoming request object
    * response The outgoing response object
    * params The parameter hash
    * session The session hash
    * controller The current controller


HTMl mixed with Ruby using tags. All of Ruby is available for programming

<% %>   # executes the Ruby code
<%= %>  # executes the Ruby code and displays the result

<% @products.each do |p| %>
  <li><%= h %></li>
<% end %>

The output of anything in <%= %> tags is directly copied to the HTML output stream. To secure against HTML injection, use the h() function to html_escape the output RXML

Creating XML files

xml.instruct!               # <?xml version="1.0" encoding="UTF-8"?>
xml.comment! "a comment"    # <!-- a comment -->
xml.feed "xmlns" => "" do
  xml.title "My Atom Feed"
  xml.subtitle h(@feed.subtitle), "type" => 'html' url_for( :only_path => false, 
                    :controller => 'feed',
                    :action => 'atom' )
  xml.updated @updated.iso8601 do "Jens-Christian Fischer" ""
  @entries.each do |entry|
    xml.entry do
      xml.title entry.title "href" => url_for ( :only_path => false,
                                   :controller => 'entries',
                                   :action => 'show',
                                   :id => entry ) entry.urn
      xml.updated entry.updated.iso8601
      xml.summary h(entry.summary)

for more details see:

RJS Properties and Methods

In addition to HTML and XML templates, Rails also understands JavaScript Templates. They allow you to easily create complex alterations of the displayed page. You can manipulate a page element with the following methods:

select - Select a DOM element for further processing'pattern') # selects an item on the page through a CSS pattern
                       # select('p'), select('p.welcome b')'div.header em').first.hide'#items li').eacj do |value|

insert_html - Inserts content into the DOM at a specific position

page.insert_html :position, id, content

position can be one of the following:

    * :top
    * :bottom
    * :before
    * :after

RJS Examples

page.insert_html :bottom, 'list', '<li>last item</li>'
page.insert_html :before, 'tasks', :partial => 'task'

replace_html Replaces the innerHTML of the specified DOM element

page.replace_html 'title', "This is the new title"
page.replace_html 'person-45', :partial => 'person', :object => @person

replace - Replaces the ‘outer HTML’

(i.e. the entire element) of the specified DOM element>

page.replace 'task', :partial => 'task', :object => @task

remove - Removes the specified DOM element

page.remove 'edit-button'

hide - Hides the specified DOM element

page.hide 'some-element'

show - Shows the specified DOM element 'some-element'

toggle - Toggle the visibility of a DOM element

page.toggle 'some-element'

alert - Displays an alert box

page.alert 'Hello world'

redirect_to - Redirects the browser to a given location

page.redirect_to :controller => 'blog', :action => 'show', :id => @post

call Calls another JavaScript function foo, 1, 2 'togleElem', page['someelement'] )

assign Assigns a value to a JS variable

page.assign "foo", 42

<< Writes raw JavaScript to the page

page << "alert('hello world);"

delay Delays the code in the block by a number of seconds

page.delay(10) do 
   page.visual_effect :fade, 'notice'

visual_effect Calls a Scriptaculous effect

page.visual_effect :highlight, 'notice', :duration => 2

sortable Create a sortable element

page.sortable 'my_list', :url => { :action => 'order' }

dragable Create a dragable element

page.dragable 'my_image', :revert => true

drop_receiving Create an element for receiving drops

page.drop_recieving 'my_cart', :url => { :controller => 'cart', :action => 'add' }

Rails Helpers

Small functions, usually used for displaying data, can be extracted to helpers. Each view has it’s own helper class (in app/helpers). Common functionality is stored in app/helpers/application_helper.rb

Rails Links Helpers

link_to "Name", :controller => 'post', :action => 'show', :id =>
link_to "Delete", { :controller => "admin",
  :action => "delete",
  :id => @post },
{ :class => 'css-class',
  :id => 'css-id',
  :confirm => "Are you sure?" }

image_tag "spinner.png", :class => "image", :alt => "Spinner"

mail_to "", "send mail", 
      :subject => "Support request by #{}",
        :cc =>,
        :body => '....',
        :encoding => "javascript"

stylesheet_link_tag “scaffold”, “admin”, :media => “all”

HTML Forms

Form Tags

<%= form_tag { :action => :save }, { :method => :post } %>

creates a form tag with the specified action, makes it a post request. Use :multipart => true to define a Mime-Multipart form (for file uploads)

Rails Text fields

<%= text_field :modelname, :attribute_name, options  %>

creates a text input field of the form:

<input type="text" name="modelname[attribute_name]" id="attributename" />

text_fielsd Example

text_field "post", "title", "size" => 20
    <input  type="text" id="post_title" name="post[title]" 
            size="20" value="#{@post.title}" />

creates a hidden field

<%= hidden_field ... %>

creates a password field (all input shown as stars)

<%= password_field ... %>

creates a file field

<%= file_field ... %>

Rails Textarea

creates a text area.

<%= text_area ... %>

text_area example

text_area "post", "body", "cols" => 20, "rows" => 40
    <textarea cols="20" rows="40" id="post_body" name="post[body]">

Radio Buttons

creates a radio button

<%= radio_button :modelname, :attribute, :tag_value, options %>

radio_button Example

radio_button "post", "category", "rails"
radio_button "post", "category", "java"
    <input type="radio" id="post_category" name="post[category]" value="rails" 
           checked="checked" />
    <input type="radio" id="post_category" name="post[category]" value="java" />

Check Box

<%= check_box :modelname, :attribute, options, on_value, off_value %>

check_box Example

check_box "post", "validated"   # post.validated? returns 1 or 0
    <input type="checkbox" id="post_validate" name="post[validated]" 
           value="1" checked="checked" />
    <input name="post[validated]" type="hidden" value="0" />

check_box "puppy", "gooddog", {}, "yes", "no"
    <input type="checkbox" id="puppy_gooddog" name="puppy[gooddog]" value="yes" />
    <input name="puppy[gooddog]" type="hidden" value="no" />


Create a select tag. Pass an array of choices

<%= select :variable, :attribute, choices, options, html_options %>

select  "post",         
        Person.find_all.collect {|p| [, ] },
        { :include_blank => true } 

 <select name="post[person_id]">
   <option value="1" selected="selected">David</option>
   <option value="2">Sam</option>
   <option value="3">Tobias</option>

Collection Selection

<%= collection_select :variable, :attribute, choices, :id, :value %>

Date Time

<%= date_select :variable, :attribute, options %>
<%= datetime_select :variable, :attribute, options %>


date_select "post", "written_on"
date_select "user", "birthday", :start_year => 1910
date_select "user", "cc_date", :start_year => 2005,
                               :use_month_numbers => true,
                               :discard_day => true,
                               :order => [:year, :month]

datetime_select "post", "written_on"

End Form Tag

<%= end_form_tag %>

Rails Layouts

A layout defines the surroundings of an HTML page. It’s the place to define common look & feel. Layouts live in app/views/layouts

    <title>Form: <%= controller.action_name %></title>
    <%= stylesheet_link_tag 'scaffold' %>
    <%= yield %>   # the content will show up here


class MyController < ApplicationController
  layout "standard", :except => [ :rss, :atom ]


class MyOtherController < ApplicationController
  layout :compute_layout

  # this method computes the name of the layout to use
  def compute_layout
    return "admin" if session[:role] == "admin"

Layouts have access to the instance variables of the controller so you can pass values ‘up’

Rails Partials

Partials are building blocks for creating views. They allow re-use of commonly used display blocks. They are stored in files:

loads the partial in _form.rthml and passed the instance variable @product to it. The partial can access it using @product

render :partial => 'product'

loads the same partial but assigns a different instance variable to it.

render :partial => 'product', :locals => { :product => @bought }

render the partial for each element in @product_list and assigns @product to each element.

render :partial => 'product', :collection => @product_list

An iteration counter will automatically be made available to the template with a name of the form partial_name_counter (in the above example: product_counter). Components

To reuse both controller logic and views, use them as ‘components’

render_component :controller => 'posts', :action => 'last_posts'

That calls last_posts in the PostsController. To render this action without a layout use

render :layout => false, ...


layout "xxx", :except => 'last_posts'

Rails Functional Tests / Testing

rake test:functional


get :action # a get request of the specificed action
get :action, :id => 1,
         { session_hash }, # optional session variables
         { flash_hash }    # optional messages in the flash

post :action, :foo => { :value1 => 'abc', :value2 => '123' },
              { :user_id => 17 },
              { :message => 'success' }

get, post, put, delete, head 

assert_response :success

possible parameters are

#   :success   
#   :redirect  
#   :missing
#   :error


assert_redirected_to :action => :other_action
assert_redirected_to :controller => 'foo', :action => 'bar'

Rendered with template

assert_template "post/index"

Variable assignments

assert_nil assigns(:some_variable)
assert_not_nil assigns(:some_variable)
assert_equal 17, assigns(:posts).size

Rendering of specific tags

assert_tag :tag => 'body'
assert_tag :content => 'Rails Seminar'
assert_tag :tag => 'div', :attributes => { :class => 'index_list' }
assert_tag :tag => 'head', :parent => { :tag => 'body' }
assert_tag :tag => 'html', :child => { :tag => 'head' }
assert_tag :tag => 'body', :descendant => { :tag => 'div' }
assert_tag :tag => 'ul',
           :children => { :count => 1..3,
                      :only => { :tag => 'li' } }

Rails AJAX

Be sure to include the javascript libraries in the layout

<%= javascript_include_tag :defaults %>

Linking to remote action

<%= link_to_remote "link", :update => 'some_div', 
                           :url => { :action => 'show', :id => } %>

<%= link_to_remote "link", :url => { :action => 'create',
                           :update => { :success => 'good_div', 
                                        :failure => 'error_div' },
                           :loading => ''spinner'),
                           :complete => 'Element.hide('spinner') } %>


:loading        Called when the remote document is being loaded with data 
                by the browser.
:loaded         Called when the browser has finished loading the remote document.
:interactive    Called when the user can interact with the remote document, 
                even though it has not finished loading.
:success        Called when the XMLHttpRequest is completed, and the HTTP 
                status code is in the 2XX range.
:failure        Called when the XMLHttpRequest is completed, and the HTTP 
                status code is not in the 2XX range.
:complete       Called when the XMLHttpRequest is complete (fires after 
                success/failure if they are present).

You can also specifiy reactions to return codes directly

link_to_remote word,
    :url => { :action => "action" },
    404 => "alert('Not found...? Wrong URL...?')",
    :failure => "alert('HTTP Error ' + request.status + '!')"

AJAX Forms

Create a form that will submit via an XMLHttpRequest instead of a POST request. The parameters are passed exactly the same way (so the controller can use the params method to access the parameters). Fallback for non JavaScript enabled browsers can be specified by using the :action methods in the :html option.

form_remote_tag :html => { :action => url_for(:controller => 'controller', 
                                              :action => 'action'), 
                           :method => :post }

Autocompleting textfield

In View

<%= text_field_with_auto_complete :model, :attribute %>

In Controller

auto_complete_for :model, :attribute

Observe Field

<label for="search">Search term:</label> 
<%= text_field_tag :search %> 
<%= observe_field(:search, 
                  :frequency => 0.5, 
                  :update => :results, 
                  :url => { :action => :search }) %> 
<div id="results"></div>

Optionally specify

:on => :blur    # trigger for event (default :changed or :clicked) 
:with => ...    # a JavaScript expression to specify what value is sent
                # defaults to "value"
:with => 'bla'  # "'bla' = value"
:with => 'a=b'  # "a=b"

Observe Form

Same semantics as observe_field

Periodically call Remote

<%= periodically_call_remote(:update => 'process-list', 
                             :url => { :action => :ps }, 
                             :frequency => 2 ) %>

Configuring your application

A lot of things can be configured in the config/environment.rb file. This list is not exhaustive: Session configuration

config.action_controller.session_store = :active_record_store 
# one of :active_record_store, :drb_store, 
# :mem_cache_store, or :memory_store or your own class

ActionController::Base.session_options[:session_key] = 'my_app'
    # use an application specific session_key
ActionController::Base.session_options[:session_id] = '12345'
    # use this session_id. Will be created if not specified
ActionController::Base.session_options[:session_expires] = 3.minute.from_now  
    # how long before a session expires?
ActionController::Base.session_options[:new_session] = true
    # force the creation of a new session
ActionController::Base.session_options[:session_secure] = true
    # only use sessions over HTTPS
ActionController::Base.session_options[:session_domain] = ''
    # Specify which domain this session is valid for (default: hostname of server)
ActionController::Base.session_options[:session_path] = '/my_app'
    # the path for which this session applies.  Defaults to the 
    # directory of the CGI script

Caching configuration

ActionController::Base.fragment_cache_store = :file_store, "/path/to/cache/directory"


Generate Mailer

Use a generator to create the mailer:

$ ruby script/generate mailer MyMailer signup_mail

This creates app/models/my_mailer.rb, app/view/my_mail/signup_mail.rhtml and test files.

Construction of Mail

Mailer “Model”

Define the mailer method:

class MyMailer < ActionMailer::Base
    def signup_mail(send_to, name, title, my_body, sent_at =
      recipients  send_to
      subject     "Signup Mail for: #{name}"
      from = ''

      @title      = title
      body       = body
      @recipients = recipient
      @from       = ''
      @sent_on    = sent_at
      @headers    = {}

Mailer “View”

Find them in app/views/my_mail/*. Just like RHTML templates, but:


will specify the Mime type of the response sent.

Create and Deliver

To create or send a mail from, just do:

mail = MyMailer.create_signup_mail("", "Joe", "your new account", "some more stuff")


MyMailer.deliver_signup_mail("", "Joe", "your new account", "some more stuff")

which will create a mail object and deliver it or create and deliver the mail in one step, respectively.


ActionMailer::Base.delivery_method = :smtp
    # alternatively: :sendmail, :test
ActionMailer::Base.server_settings = {
   :address => "",
   :port => 25,
   :domain => '',
   :user_name => "username",
   :password => "password",
   :authentication => :login  # possible values :plain, :login, :cram_md5

ActionMailer::Base.template_root = "mailer/templates" 
  # mailer will look for rhtml templates in that path
  # example: "mailer/templates/my_mailer/signup_mail.rhtml"
ActionMailer::Base.perform_deliveries = true # the "deliver_*" methods are available
ActionMailer::Base.raise_delivery_errors = true
ActionMailer::Base.default_charset = "utf-8"
ActionMailer::Base.default_content_type = "text/html" # default: "text/plain"
ActionMailer::Base.default_mime_version = "1.0" 
ActionMailer::Base.default_implicit_parts_order = [ "text/html", "text/plain"]

Some of the settings can be overridden in the mailer method body:

def my_mail
  @charset = "utf-8"
  @content_type = "text/html"
  @mime_version = "1.0"
  @implicit_parts_order = [ "text/plain", "text/html"]


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Part of the course materials for the Ruby On Rails Workshop by InVisible GmbH. Jens-Christian Fischer authored the original reference
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This reference guide is © 2006 by InVisible GmbH ( and released under a Creative Commons license.