Module: ActionController::Resources

Included in:: ActionController::Routing::RouteSet::Mapper

Defined in:: lib/action_controller/resources.rb

Overview

ActionController::Resources are a way of defining RESTful resources. A RESTful resource, in basic terms, is something that can be pointed at and it will respond with a representation of the data requested. In real terms this could mean a user with a browser requests an HTML page, or that a desktop application requests XML data.

RESTful design is based on the assumption that there are four generic verbs that a user of an application can request from a resource (the noun).

Resources can be requested using four basic HTTP verbs (GET, POST, PUT, DELETE), the method used denotes the type of action that should take place.

The Different Methods and their Usage

GET Requests for a resource, no saving or editing of a resource should occur in a GET request POST Creation of resources PUT Editing of attributes on a resource DELETE Deletion of a resource

Examples

# A GET request on the Posts resource is asking for all Posts
GET /posts

# A GET request on a single Post resource is asking for that particular Post
GET /posts/1

# A POST request on the Posts resource is asking for a Post to be created with the supplied details
POST /posts # with => { :post => { :title => "My Whizzy New Post", :body => "I've got a brand new combine harvester" } }

# A PUT request on a single Post resource is asking for a Post to be updated
PUT /posts # with => { :id => 1, :post => { :title => "Changed Whizzy Title" } }

# A DELETE request on a single Post resource is asking for it to be deleted
DELETE /posts # with => { :id => 1 }

By using the REST convention, users of our application can assume certain things about how the data is requested and how it is returned. Rails simplifies the routing part of RESTful design by supplying you with methods to create them in your routes.rb file.

Read more about REST at en.wikipedia.org/wiki/Representational_State_Transfer

Defined Under Namespace

Classes: Resource, SingletonResource

Instance Method Summary collapse

#resource(*entities, &block) ⇒ Object

Creates named routes for implementing verb-oriented controllers for a singleton resource.
#resources(*entities, &block) ⇒ Object

Creates named routes for implementing verb-oriented controllers for a collection resource.

Instance Method Details

#resource(*entities, &block) ⇒ `Object`

Creates named routes for implementing verb-oriented controllers for a singleton resource. A singleton resource is global to its current context. For unnested singleton resources, the resource is global to the current user visiting the application, such as a user’s /account profile. For nested singleton resources, the resource is global to its parent resource, such as a projects resource that has_one :project_manager. The project_manager should be mapped as a singleton resource under projects:

map.resources :projects do |project|
  project.resource :project_manager
end

See map.resources for general conventions. These are the main differences:

A singular name is given to map.resource. The default controller name is still taken from the plural name.
To specify a custom plural name, use the :plural option. There is no :singular option.
No default index route is created for the singleton resource controller.
When nesting singleton resources, only the singular name is used as the path prefix (example: ‘account/messages/1’)

For example:

map.resource :account

maps these actions in the Accounts controller:

class AccountsController < ActionController::Base
  # GET new_account_url
  def new
    # return an HTML form for describing the new account
  end

  # POST account_url
  def create
    # create an account
  end

  # GET account_url
  def show
    # find and return the account
  end

  # GET edit_account_url
  def edit
    # return an HTML form for editing the account
  end

  # PUT account_url
  def update
    # find and update the account
  end

  # DELETE account_url
  def destroy
    # delete the account
  end
end

Along with the routes themselves, #resource generates named routes for use in controllers and views. map.resource :account produces these named routes and helpers:

Named Route   Helpers
============  =============================================
account       account_url, hash_for_account_url,
              account_path, hash_for_account_path

new_account   new_account_url, hash_for_new_account_url,
              new_account_path, hash_for_new_account_path

edit_account  edit_account_url, hash_for_edit_account_url,
              edit_account_path, hash_for_edit_account_path

# File 'lib/action_controller/resources.rb', line 384

def resource(*entities, &block)
  options = entities.extract_options!
  entities.each { |entity| map_singleton_resource(entity, options.dup, &block) }
end

#resources(*entities, &block) ⇒ `Object`

Creates named routes for implementing verb-oriented controllers for a collection resource.

For example:

map.resources :messages

will map the following actions in the corresponding controller:

class MessagesController < ActionController::Base
  # GET messages_url
  def index
    # return all messages
  end

  # GET new_message_url
  def new
    # return an HTML form for describing a new message
  end

  # POST messages_url
  def create
    # create a new message
  end

  # GET message_url(:id => 1)
  def show
    # find and return a specific message
  end

  # GET edit_message_url(:id => 1)
  def edit
    # return an HTML form for editing a specific message
  end

  # PUT message_url(:id => 1)
  def update
    # find and update a specific message
  end

  # DELETE message_url(:id => 1)
  def destroy
    # delete a specific message
  end
end

Along with the routes themselves, #resources generates named routes for use in controllers and views. map.resources :messages produces the following named routes and helpers:

Named Route   Helpers
============  =====================================================
messages      messages_url, hash_for_messages_url,
              messages_path, hash_for_messages_path

message       message_url(id), hash_for_message_url(id),
              message_path(id), hash_for_message_path(id)

new_message   new_message_url, hash_for_new_message_url,
              new_message_path, hash_for_new_message_path

edit_message  edit_message_url(id), hash_for_edit_message_url(id),
              edit_message_path(id), hash_for_edit_message_path(id)

You can use these helpers instead of #url_for or methods that take #url_for parameters. For example:

redirect_to :controller => 'messages', :action => 'index'
# and
<%= link_to "edit this message", :controller => 'messages', :action => 'edit', :id => @message.id %>

now become:

redirect_to messages_url
# and
<%= link_to "edit this message", edit_message_url(@message) # calls @message.id automatically

Since web browsers don’t support the PUT and DELETE verbs, you will need to add a parameter ‘_method’ to your form tags. The form helpers make this a little easier. For an update form with a @message object:

<%= form_tag message_path(@message), :method => :put %>

<% form_for :message, @message, :url => message_path(@message), :html => {:method => :put} do |f| %>

The #resources method accepts the following options to customize the resulting routes:

:collection - add named routes for other actions that operate on the collection. Takes a hash of #{action} => #{method}, where method is :get/:post/:put/:delete or :any if the method does not matter. These routes map to a URL like /messages/rss, with a route of rss_messages_url.
:member - same as :collection, but for actions that operate on a specific member.
:new - same as :collection, but for actions that operate on the new resource action.
:controller - specify the controller name for the routes.
:singular - specify the singular name used in the member routes.
:requirements - set custom routing parameter requirements.
:conditions - specify custom routing recognition conditions. Resources sets the :method value for the method-specific routes.

:path_prefix - set a prefix to the routes with required route variables.

Weblog comments usually belong to a post, so you might use resources like:

map.resources :articles
map.resources :comments, :path_prefix => '/articles/:article_id'

You can nest resources calls to set this automatically:

map.resources :articles do |article|
  article.resources :comments
end

The comment resources work the same, but must now include a value for :article_id.

article_comments_url(@article)
article_comment_url(@article, @comment)

article_comments_url(:article_id => @article)
article_comment_url(:article_id => @article, :id => @comment)

:name_prefix - define a prefix for all generated routes, usually ending in an underscore. Use this if you have named routes that may clash.

map.resources :tags, :path_prefix => '/books/:book_id', :name_prefix => 'book_'
map.resources :tags, :path_prefix => '/toys/:toy_id',   :name_prefix => 'toy_'

You may also use :name_prefix to override the generic named routes in a nested resource:

map.resources :articles do |article|
  article.resources :comments, :name_prefix => nil
end

This will yield named resources like so:

comments_url(@article)
comment_url(@article, @comment)

If map.resources is called with multiple resources, they all get the same options applied.

Examples:

map.resources :messages, :path_prefix => "/thread/:thread_id"
# --> GET /thread/7/messages/1

map.resources :messages, :collection => { :rss => :get }
# --> GET /messages/rss (maps to the #rss action)
#     also adds a named route called "rss_messages"

map.resources :messages, :member => { :mark => :post }
# --> POST /messages/1/mark (maps to the #mark action)
#     also adds a named route called "mark_message"

map.resources :messages, :new => { :preview => :post }
# --> POST /messages/new/preview (maps to the #preview action)
#     also adds a named route called "preview_new_message"

map.resources :messages, :new => { :new => :any, :preview => :post }
# --> POST /messages/new/preview (maps to the #preview action)
#     also adds a named route called "preview_new_message"
# --> /messages/new can be invoked via any request method

map.resources :messages, :controller => "categories",
      :path_prefix => "/category/:category_id",
      :name_prefix => "category_"
# --> GET /categories/7/messages/1
#     has named route "category_message"

The #resources method sets HTTP method restrictions on the routes it generates. For example, making an HTTP POST on new_message_url will raise a RoutingError exception. The default route in config/routes.rb overrides this and allows invalid HTTP methods for resource routes.

# File 'lib/action_controller/resources.rb', line 310

def resources(*entities, &block)
  options = entities.extract_options!
  entities.each { |entity| map_resource(entity, options.dup, &block) }
end

Module: ActionController::Resources

Overview

Overview

The Different Methods and their Usage

Examples

Defined Under Namespace

Instance Method Summary collapse

Instance Method Details

#resource(*entities, &block) ⇒ Object

#resources(*entities, &block) ⇒ Object

#resource(*entities, &block) ⇒ `Object`

#resources(*entities, &block) ⇒ `Object`