Module | ActionController::Resources
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

### Methods

resource resources

### Public Instance methods

resource(*entities, &block)

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

resources(*entities, &block)

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 %>

or

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

or

      <% form_for @message do |f| %>

which takes into account whether `@message` is a new record or not and generates the path and method accordingly.

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.
- `:as` - Specify a different resource name to use in the URL path. For example:

        # products_path == '/productos'
        map.resources :products, :as => 'productos' do |product|
          # product_reviews_path(product) == '/productos/1234/comentarios'
          product.resources :product_reviews, :as => 'comentarios'
        end

- `:has_one` - Specify nested resources, this is a shorthand for mapping singleton resources beneath the current.
- `:has_many` - Same has `:has_one`, but for plural resources.

  You may directly specify the routing association with `has_one` and `has_many` like:

        map.resources :notes, :has_one => :author, :has_many => [:comments, :attachments]

  This is the same as:

        map.resources :notes do |notes|
          notes.resource  :author
          notes.resources :comments
          notes.resources :attachments
        end

- `:path_names` - Specify different names for the ‘new’ and ‘edit’ actions. For example:

        # new_products_path == '/productos/nuevo'
        map.resources :products, :as => 'productos', :path_names => { :new => 'nuevo', :edit => 'editar' }

  You can also set default action names from an environment, like this:

        config.action_controller.resources_path_names = { :new => 'nuevo', :edit => 'editar' }

- `: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.

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