Installing a gem in fair enough but what if you don’t know what it’s called?

Well, one way of finding a gem is to look at the rubygems homepage at http://rubyforge.org/projects/rubygems/

However, this can be a bit overwhelming and may be a long way around if you know what you are looking for. In cases like these you can search a remote list of gems for the phrase you are after:

gem search mysql --remote gems.rubyforge.org

This will give a list of gems with the word ‘mysql’ in them.

Installing

Installing a particular gem is very simple:

sudo gem install mysql

That will, not unsurprisingly, install the gem ‘mysql’ (which is the ruby bindings for MySQL, not MySQL itself!).

The example above will give a choice of versions to install. On a Linux VPS simply choose the latest ‘ruby’ version. So at the time of writing I would select option (3) mysql 2.7 (ruby).

Often a gem will have several dependencies with it. To stop the install asking if you want the dependencies to be installed use this:

sudo gem install mysql --include-dependencies

Outdated

To get a list of gems that are now outdated (they have a newer version available), use this command:

gem outdated

Updating

To update all the installed rubygems is just as straightforward:

gem update

However, you may not want to update all at once, in which case specify the gem:

gem update mysql

Clean

This will remove outdated versions of gems that are installed, leaving the new updated version installed:

gem clean

This will leave a nice and shiny up to date rubygems install.

Removing

At some point you may want to get rid of a gem completely. No problem:

sudo gem uninstall mysql

Listing installed gems

To get a list of locally installed gems, issue this command:

gem list

That will give an overview of the gems you have installed.

This reference guide is © 2006 by InVisible GmbH (http://www.invisible.ch) and released under a Creative Commons license (see end for details). More information and a PDF version of this document can be found at http://blog.invisible.ch/2006/05/01/ruby-on-rails-reference/.

Railties

Create a rails application

$ rails app_name

Options:

• -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

Rake

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

Scripts

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

script/process/reaper
script/process/spawner

Generators

ruby script/generate model ModelName
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

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)

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 http://invisible.ch/projects/plugins/where
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.

Models

Object creation

Model.new   # creates a new empty model
Model.create( :field => 'value',   ther_field => 42 )
# creates an object with the passed parameters and saves it

Model.find_or_create_by_field( value )
# searches for a record where "field = value", creates
# a new record if not found

User.find_or_create_by_name_and_email( 'joe', 'joe@example.com')

Model Relations

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

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

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

def Customer <  ActiveRecord::Base
has_many   rders
has_one :address
end

def Address <  ActiveRecord::Base
belongs_to :customer
end

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
  rder       => '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

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

Table categories_products with category_id and product_id (without id column)

Association Join Models

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

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

class Book <  ActiveRecord::Base
has_one :authorship
end

@author = Author.find :first
@author.authorships.collect { |a| a.book } # 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
end

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

class Invoice <  ActiveRecord::Base
belongs_to :client
end

@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.

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 => /^(+)@((?:[-a-z0-9]+.)+[a-z]{2,})$/i

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

validates_inclusion_of  :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
  n      => :create                 # or :update (validates only then)
:if      => ...                     # call method oder Proc

Calculations

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

Find

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:

  rder => 'name DESC'       # sql fragment for sorting
  ffset => 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

Scope

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')
end

# 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
end
end

for more details and examples, see:

• http://www.codyfauser.com/articles/2006/02/01/using-with_scope-to-refactor-messy-finders
• http://blog.caboo.se/articles/2006/02/22/nested-with_scope

Callbacks

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

Examples:

class Subscription <  ActiveRecord::Base
before_create :record_signup
private
def record_signup
self.signed_up_on = Date.today
end
end

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

Observers

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

class CommentObserver <  ActiveRecord::Observer
def after_save(comment)
Notifications.deliver_comment("admin@do.com", "New comment was posted", comment)
end
end

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

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 
# regular table
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
end

# join table for has_and_belongs_to_many (note: no id column!)
create_table :modelas_modelbs, :id => false do |t|
t.column :modela_id, :integer
t.column :modelb_id, :integer
end

add_column :table, :column, :type
rename_column :table,   ld_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 ]
end

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

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, @p.id       # equality
assert_match /regexp/, test # regular expression
@product.destroy
assert_raise(ActiveRecord::RecordNotFound) { Product.find( @product.id ) }

Controllers

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'
end

Parameters are stored in the params hash:

/world/hello/1?foo=bar
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])
end

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" }
end
end

Render

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

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'

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'

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

File

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

Text

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'

Inline Template

Uses ERb to render the “miniature” template

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

Nothing

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

RJS

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

Change the content-type:

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

URL Routing

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}/ }

Filter

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 :authenticate,   nly => [ :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

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] %>
< % end %>

Session management

It’s possible to turn off session management:

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

Cookies

Setting

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

Reading

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

Deleting

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.

File Uploads

Define a multipart form in your view:

< %= form_tag( { :action => 'upload' }, :multipart => true ) -%>
Upload file: < %= file_field( "form", "file" ) -%>
< br />
< %= submit_tag( "Upload file" ) -%>
< %= end_form_tag %>

Handle the upload in the controller:

def upload
file_field = @params['form']['file'] rescue nil
# file_field is a StringIO object
file_field.content_type # 'text/csv'
file_field.full_original_filename
...
end

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

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

< ul>
< % @products.each do |p| %>
>< %= h @p.name %>

< % 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

Creates XML files

xml.instruct!               # < ?xml version="1.0" encoding="UTF-8"?>
xml.comment! "a comment"    # 
xml.feed "xmlns" => "http://www.w3.org/2005/Atom" do
xml.title "My Atom Feed"
xml.subtitle h(@feed.subtitle), "type" => 'html'
xml.link url_for(   nly_path => false,
:controller => 'feed',
:action => 'atom' )
xml.updated @updated.iso8601
xml.author do
xml.name "Jens-Christian Fischer"
xml.email "jcfischer@gmail.com"
end
@entries.each do |entry|
xml.entry do
xml.title entry.title
xml.link "href" => url_for (   nly_path => false,
:controller => 'entries',
:action => 'show',
:id => entry )
xml.id entry.urn
xml.updated entry.updated.iso8601
xml.summary h(entry.summary)
end
end
end

for more details see: http://rubyforge.org/projects/builder/

RJS

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

page.select('pattern') # selects an item on the page through a CSS pattern
# select('p'), select('p.welcome b')
page.select('div.header em').first.hide
page.select('#items li').each do |value|
value.hide
end

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

Examples:

page.insert_html :bottom, 'list', '
last item

'
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',   bject => @person

replace Replaces the “outer HTML”, (i.e. the entire element) of the specified DOM element

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

page.show 'some-element'

toggle Toggle the visibility of a DOM element

page.toggle 'some-element'

alert Display 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

page.call foo, 1, 2

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'
end

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' }

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

Links

link_to "Name", :controller => 'post', :action => 'show', :id => @post.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 "info@invisible.ch", "send mail",
:subject => "Support request by #{@user.name}",
:cc => @user.email,
:body => '....',
:encoding => "javascript"

stylesheet_link_tag "scaffold", "admin", :media => "all"

HTML Forms

Form_for

< % form_for :person, @person, :url => { :action => "update" },
:html => {:id => 'person_form'} do |f| %>
First name: < %= f.text_field :first_name %>
Last name : < %= f.text_field :last_name %>
Age       : < %= f.text_field :age, :size => 2 %>
Biography : < %= f.text_area :biography %>
Admin?    : < %= f.check_box :admin %>
< % end %>

You can use all the following functions in the form_for and remote_form_for blocks and leave out the model part:

fields_for ###

Same as form_for, but does not wrap it in form tags. allows you to have fields for secondary objects:

< % form_for :person, @person, :url => { :action => "update" } do |person_form| %>
First name: < %= person_form.text_field :first_name %>
Last name : < %= person_form.text_field :last_name %>

< % fields_for :permission, @person.permission do |permission_fields| %>
Admin?  : < %= permission_fields.check_box :admin %>
< % end %>
< % end %>

Form

< %= form_tag :action => 'update', :id => @some_object %>

< %= 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)

< %= form_tag( {:action => 'upload'}, :multipart => true ) %>

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" />

Example:

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

< %= hidden_field ... %>

creates a hidden field

< %= password_field ... %>

creates a password field (all input shown as stars)

< %= file_field ... %>

creates a file field

Textarea

< %= text_area ... %>

creates a text area. Example:

text_area "post", "body", "cols" => 20, "rows" => 40
< textarea cols="20" rows="40" id="post_body" name="post[body]">
#{@post.body}
textarea>

Radio Button

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

creates a 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 %>

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" />

Options

Create a select tag. Pass an array of choices

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

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

< select name="post[person_id]">
< option>option>
David< /option>
< option value="2">Samoption>
Tobias< /option>
select>

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

Date Time

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

Examples:

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,
  rder => [:year, :month]

datetime_select "post", "written_on"

End Form Tag

< %= end_form_tag %>

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

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

----

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

----

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"
"standard"
end
...
end

Layouts have access to the instance variables of the controller so you can pass values “up”

Partials

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

render :partial => 'product'

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

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

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

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

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

render :layout => false, ...

or

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

to render this action without a layout

Functional Testing

rake test:functional

Requests

get :action # a get request of the specificed action
get :action, { :id => 1 }, # use {} only if you use session/flash hash
{ 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

AJAX Requests

xhr :get, :action  # make an "Ajax" Requests to of the specified action
xhr :post,   ther_action, {:foo => { :value1 => 'abc', :value2 => '123' }}}

Redirects

assert_redirected_to :action =>   ther_action
assert_redirected_to :controller => 'foo', :action => 'bar'
assert_redirected_to http://www.invisible.ch

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,
  nly => { :tag => 'li' } }

Asserting that specific tag was NOT rendered

assert_no_tag :tag => 'div', :attributes => { :id => 'some_id' }

Assertions regarding routing

Test that some options generate a specific path:

assert_generates 'books/edit/2', { :controller => 'books', :action => 'edit', :id => 2 }

The test to see, if a route is recognized is, user assert_recognizes

assert_recognizes { :controller => 'projects', :action => 'list' }, 'projects/list'

To test both assertion in one go, use

assert_routing 'users/show/2', { :controller => 'users', :action => 'show', :id => 2 }

Testing HTML generation

Use this to test helper functions that generate HTML snippets. The two assertions are looking for a match on the DOM level (that means, that attributes could appear in any order without the test breaking)

assert_dom_equal "\"http://www.example.com\">Example", link_to "Example", "http://www.example.com"

and it’s sibling:

assert_dom_not_equal

Testing for valid record

Asserts that the record is valid (i.e. hasn’t any error messages when saving)

assert_valid @book

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 => post.id } %>

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

Callbacks

: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>

Optionally specify:

  n => :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] = 'invisible.ch'
# 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"

ActionMailer

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 = Time.now)
recipients  send_to
subject     "Signup Mail for: #{name}"
from = 'someonone@example.com'

@title      = title
body       = body
@recipients = recipient
@from       = 'someone@example.com'
@sent_on    = sent_at
@headers    = {}
end
end

Mailer “View”

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

signup_mail.text.plain.rhtml
signup_mail.text.html.rhtml
...

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@doe.com", "Joe", "your new account", "some more stuff")
MyMailer.deliver(mail)

or

MyMailer.deliver_signup_mail("joe@doe.com", "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.

Testing

def test_signup_mail
MyMailer.deliver_signup_mail("joe@doe.com", "Joe", "your new account",
"some_more_stuff", @expected.date)
assert !ActionMailer::Base.deliveries.empty?

sent = ActionMailer::Base.deliveries.first
assert_equal 'joe@doe.com', sent.to.first
assert_equal "your new account", sent.subject
assert_equal "info@my_corp.com", sent.from.first
assert sent.body =~ /^some more stuff/
end

Configure

ActionMailer::Base.delivery_method = :smtp
# alternatively: :sendmail, :test
ActionMailer::Base.server_settings = {
:address => "mail.mydomain.com",
:port => 25,
:domain => 'mydomain.com',
: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"]
end

Appendix

Changelog

Changelog

Sources

• Agile Web Development with Rails
• The Rails-Users mailing list
• The Rails Source code

License

Part of the course materials for the Ruby On Rails Workshop by InVisible GmbH.

InVisible GmbH
Schweighofstrasse 312
8055 Zürich
+41 44 401 09 30

http://www.invisible.ch

mailto:info@invisible.ch