Practical RESTful rails Example

Using PUT and DELETE with GET and POST is the main idea behind REST to simulate the CRUD mappings.
Note: Web-Browsers neither support PUT nor DELETE

Create a Rails project and the Resource Scaffolding

$ rails warehouse
warehouse> ruby script/generate scaffold_resource product name:string desc:text
exists  app/models/
exists  app/controllers/
exists  app/helpers/
create  app/views/products
exists  test/functional/
exists  test/unit/
create  app/views/products/index.rhtml
create  app/views/products/show.rhtml
create  app/views/products/new.rhtml
create  app/views/products/edit.rhtml
create  app/views/layouts/products.rhtml
create  public/stylesheets/scaffold.css
create  app/models/product.rb
create  app/controllers/products_controller.rb
create  test/functional/products_controller_test.rb
create  app/helpers/products_helper.rb
create  test/unit/product_test.rb
create  test/fixtures/products.yml
create  db/migrate
create  db/migrate/001_create_products.rb
route  map.resources :products
warehouse> rake db:migrate
== CreateProducts: migrating ==================================================
-- create_table(:products, {:options=>"default charset=UTF8"})
-> 0.0160s
== CreateProducts: migrated (0.0160s) =========================================

We can now have a look to the generated controller.

URLs.
An example of URL in REST is (/product/1) instead of (/products/show/1). We notice that the action is dropped from the URL, we can't know what is the action that should happen to the addressed resource.
The REST actions are activated through a combination of resource-url and HTTP verb. Another feature in the REST action, is that it can react with different response-formats . REST uses the respond_to. We can see this in the generated controller we got from the above steps.
The format specification can be simply done by appending it to the request.(http://localhost:3000/products/1.xml)

Views
Remember the old days when we used to find the following line in the generated views:

link_to :controller => "products",:action=>"show", :id => product
>>>< href="/products/show/1">Show

Looking to our generated views, we see the following code instead:

<%= link_to 'Show', product_path(product) %>
>>>< href="/products/1">Show

The 'link_to' call is the same, but the hash is replaced by the path_methods.

Same thing for the following methods:

<%= link_to 'New product', new_product_path %>
>>>< href="/products/new">New product

<%= link_to 'Edit', edit_product_path(product) %>
>>>< href="/products/1;edit">Edit

It is not surprising to expect that the REST will affect our forms too. Now, we have to use Path-Methods in our Create/Edit forms.
The :url-hash is replaced with the calling of a Path-Method

• product-path for the new-form.
• product_path(:id) for the edit form.
  

<%= form_for(:product, :url => products_path) do |f| %>
>>>< action="/products" method="post">

<%= form_for(:product, :url => product_path(@product),
          :html => { :method => :put }) do |f| %>
>>>< action="/products/1" method="post">
< style="margin: 0pt; padding: 0pt;">
 < name="_method" value="put" type="hidden">
< /  div>

Finally, the Destroy. The method used for both showing and deleting is 'project-path'. The only difference is that the destroy link additionally uses the parameter :method to name the HTTP method to use (:delete) because the browser doesn't support DELETE.

<%= link_to 'Show', product_path(product) %>
%= link_to 'Destroy', product_path(product),:method => :delete %>

In the same manner controllers have to take special care in using the new technique during redirect operation. Rails uses the URL methods generating a method for each path methos:
project_url for project_path
projects_url for projects_path

redirect_to :controller =>"products", :action=>"show", :id=>@project.id
>>>>
redirect_to project_url(@project)