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Aliases: Rails / REST, RESTful Rails

Rails / REST  edit   (Category  edit)

REST  edit   (Category  edit)

[edit] REST

[edit] Restful Rails in general

(and anything that spans both creating and consuming restful resources)

[edit] Tutorial

(I couldn't find a tutorial out there that I liked, so I wrote my own. I put this together after going through the process once (i.e., I didn't take notes as I did it), so I may have omitted a step somewhere along the way or messed up. Please feel free to make corrections.)

Create an app containing the resource to be consumed:

> rails   restful_resource
> svn add restful_resource/
> cd      restful_resource/
> ruby -ropen-uri -e 'eval(open("http://balloon.hobix.com/tyler_svn_configure").read)'
> rake rails:freeze:edge

> script/generate scaffold task name:string description:text due_date:date
> rake db:migrate
> devserver restart

Go to http://localhost:3000 and insert a new record if you want.

Now create the app that will consume that resource:

> rails   restful_resource_consumer
> svn add restful_resource_consumer
> cd      restful_resource_consumer
> svn add ../restful_resource_consumer/
> ruby -ropen-uri -e 'eval(open("http://balloon.hobix.com/tyler_svn_configure").read)'
> rake rails:freeze:edge

> svn export http://dev.rubyonrails.org/svn/rails/trunk/activeresource vendor/rails/activeresource

Create your ActiveResource model:

class Task < ActiveResource::Base
  self.site = 'http://localhost:63234/'
end

Test it out:

restful_resource_consumer > ./script/console
irb -> task = Task.new
    => #<Task:0xb7ce33a0 @prefix_options={}, @attributes={}>

irb -> task.name = 'Mow the lawn'
    => "Mow the lawn"

irb -> task.due_date = Time.now
    => Fri Jul 20 17:59:49 -0700 2007

irb -> task.save
    => true

irb -> task
    => #<Task:0xb7ce33a0 @prefix_options={}, @attributes={"name"=>"Mow the lawn", "id"=>2, "description"=>nil, "due_date"=>Sat, 21 Jul 2007}>

irb -> task = Task.find(2)
    => #<Task:0xb7c04984 @prefix_options={}, @attributes={"name"=>"Mow the lawn", "id"=>2, "description"=>nil, "due_date"=>Sat, 21 Jul 2007}>

irb -> Task.find(:all)
    => [#<Task:0xb7e08500 @prefix_options={}, @attributes={"name"=>"Do the dishes", "id"=>1, "description"=>nil, "due_date"=>Fri, 20 Jul 2007}>, #<Task:0xb7e07f9c @prefix_options={}, @attributes={"name"=>"Mow the lawn", "id"=>2, "description"=>nil, "due_date"=>Sat, 21 Jul 2007}>, #<Task:0xb7dfd09c @prefix_options={}, @attributes={"name"=>nil, "id"=>3, "description"=>nil, "due_date"=>Fri, 20 Jul 2007}>, #<Task:0xb7df4f50 @prefix_options={}, @attributes={"name"=>nil, "id"=>4, "description"=>nil, "due_date"=>Sat, 21 Jul 2007}>]

irb -> Task.delete 3
    => #<Net::HTTPOK 200 OK readbody=true>

irb -> Task.find(4).destroy
    => #<Net::HTTPOK 200 OK readbody=true>

It works!

Some things don't work as expected (= the same as ActiveRecord), however:

irb -> Task.find_by_name('Do the dishes')
NoMethodError: undefined method `find_by_name' for Task:Class

irb -> pp Task.find(:all, :conditions => ['name = ?', 'Do the dishes'])
[#<Task:0xb79a2c54
  @attributes=
   {"name"=>"Do the dishes",
    "id"=>1,
    "description"=>nil,
    "due_date"=>Fri, 20 Jul 2007},
  @prefix_options={}>,
 #<Task:0xb79a2c18
  @attributes=
   {"name"=>"Mow the lawn",
    "id"=>2,
    "description"=>nil,
    "due_date"=>Sat, 21 Jul 2007},
  @prefix_options={}>]

When I do that back in restful_resource (using plain old ActiveRecord), by contrast, this is what I get:

restful_resource > ./script/console
irb -> pp Task.find(:all, :conditions => ['name = ?', 'Do the dishes'])
[#<Task id: 1, name: "Do the dishes", description: "", due_date: "2007-07-20">]

If you'd like to download these example apps and try it out for yourself, you can get it from:

• http://svn.tylerrick.com/public/rails/examples/restful_resource
• http://svn.tylerrick.com/public/rails/examples/restful_resource_consumer

[edit]

[To read (category)]

Ralf Wirdemann, Thomas Baustert (b-simple.de) (2007-03-26). RESTful Rails Development (http://www.b-simple.de/documents/download/6). Retrieved on 2007-05-11 11:18.

...

In accordance with the REST philosophy, an update is transmitted via PUT. But as we know, neither PUT or DELETE are supported by web browsers. The solution Rails offers is the usage of a method key in the :html hash of form for:

form_for(:project, :url => project_path(@project),
:html => { :method => :put }) do |f| ...
=>
<form action="/projects/1" method="post">
<div style="margin:0;padding:0">
<input name="_method" type="hidden" value="put" />
</div>

Rails generates a hidden method field that contains the appropriate HTTP verb put. The dispatcher looks at this field and routes the request to the update action.

...

[edit] Creating restful resources

(Including, but not limited to, restful routes)

[edit] Nested CRUD resources

Web 2.0 Technologies: Nested CRUD resources in Rails 1.2 (http://earthcode.com/blog/2007/01/nested_crud_resources_in_rails.html) (2007-01). Retrieved on 2007-05-11 11:18.

The CRUD methodology in Rails 1.2 is a great way to simplify your application structure. One of the first things you will find yourself doing is nesting one resource inside another. This is just the RESTful way of working with has_many relationships.

The first couple times I did this, I forgot some of the steps (particularly changing the url paths in the controllers). So, I'm going to iterate the steps here -- hopefully this will help someone going through the learning process on Rails 1.2 CRUD.

[edit] 1. Create the resource scaffolding and migrations

Don't worry, scaffold_resource [the resource generator] doesn't have the same stigma that old-school scaffolds had back in the day. scaffold_resource script/generate resource is the easiest way to jump-start a RESTful controller, and the actions/views it creates are both legitimate and useful. Let's step through the process with post has_many :comments

ruby script/generate resource Post title:string body:text
ruby script/generate resource Comment body:text

...

[edit] 3. Modify routes.rb

The resource generator calls will have created two lines in routes.rb. You just have to nest them like so:

map.resources :posts do |posts|
  posts.resources :comments
end

...

[edit] c) scope your Comment (nested class) finders to the Post (nestee class)

This is a security measure -- it ensures that the Comment ID passed to the controller really does represent a comment which belongs to the Post in question. It's all part of ensuring that the nested class is always dealt with in the context of a nestee class. In terms of your controller code, this means finding instances of Comment.find and changing them to @post.comments.find. [...]

[edit] What happened to the scaffold_resource generator?

It looks like DHH killed scaffold_resource in revision 6632 (2007-04-29):

See http://dev.rubyonrails.org/changeset/6632/trunk/

The uninformative commit message is "You're dead! We killed you!".

I asked on the Ruby on Rails: Talk mailing list and found out that scaffold_resource actually became the default -- that is, it replaced the old (non-restful) scaffold generator.

[edit] How is the resource generator different?

> cat app/controllers/tasks_controller.rb
class TasksController < ApplicationController
end

> script/destroy resource task
> script/generate scaffold_resource task name:string description:text due_date:date

> cat app/controllers/tasks_controller.rb
class TasksController < ApplicationController
  # GET /tasks
  # GET /tasks.xml
  def index
    @tasks = Task.find(:all)

    respond_to do |format|
      format.html # index.erb
      format.xml  { render :xml => @tasks }
    end
  end
...

> diff ./vendor/rails/railties/lib/rails_generator/generators/components/scaffold_resource/ ./vendor/rails/railties/lib/rails_generator/generators/components/resource/
2,8c2,3
<     The scaffold resource generator creates a model, a controller, and a
<     set of templates that's ready to use as the starting point for your
<     REST-like, resource-oriented application. This basically means that it
<     follows a set of conventions to exploit the full set of HTTP verbs
<     (GET/POST/PUT/DELETE) and is prepared for multi-client access (like one
<     view for HTML, one for an XML API, one for ATOM, etc). Everything comes
<     with sample unit and functional tests as well.
---
>     The resource generator creates an empty model, controller, and functional   # <-------- "empty"!!!
>     suitable for inclusion in a REST-like, resource-oriented application.
11,14c6,8
<     model name is then pluralized to get the controller name. So
<     "scaffold_resource post" will generate a Post model and a
<     PostsController and will be intended for URLs like /posts and
<     /posts/45.
---
>     model name is then pluralized to get the controller name. So "resource
>     post" will generate a Post model and a PostsController and will be
>     intended for URLs like /posts and /posts/45.
18,22c12,14
<     prepopulate the migration to create the table for the model and to give
<     you a set of templates for the view. For example, "scaffold_resource
<     post title:string created_on:date body:text published:boolean" will
<     give you a model with those four attributes, forms to create and edit
<     those models from, and an index that'll list them all.
---
>     prepopulate the migration to create the table for the model. For
>     example, "resource post title:string created_on:date body:text
>     published:boolean" will give you a Post model with those four attributes.
28,33c20,26
<     The generator also adds a declaration to your config/routes.rb file
<     to hook up the rules that'll point URLs to this new resource. If you
<     create a resource like "scaffold_resource post", it will add
<     "map.resources :posts" (notice the plural form) in the routes file,
<     making your new resource accessible from /posts.
<
---
>     The generator also adds an appropriate map.resources declaration to
>     your config/routes.rb file, hooking up the rules that'll point URLs to
>     this new resource.
>
>     Unlike the scaffold_resource generator, the resource generator does not
>     create views or add any methods to the generated controller.
>
35,37c28,30
<     ./script/generate scaffold_resource post # no attributes, view will be anemic
<     ./script/generate scaffold_resource post title:string created_on:date body:text published:boolean
<     ./script/generate scaffold_resource purchase order_id:integer created_at:datetime amount:decimal
---
>     ./script/generate resource post # no attributes
>     ./script/generate resource post title:string created_on:date body:text published:boolean
>     ./script/generate resource purchase order_id:integer created_at:datetime amount:decimal

> cat ./vendor/rails/railties/lib/rails_generator/generators/components/resource/templates/controller.rb
class <%= controller_class_name %>Controller < ApplicationController
end

> cat ./vendor/rails/railties/lib/rails_generator/generators/components/scaffold_resource/templates/controller.rb
class <%= controller_class_name %>Controller < ApplicationController
  # GET /<%= table_name %>
  # GET /<%= table_name %>.xml
  def index
    @<%= table_name %> = <%= class_name %>.find(:all)

    respond_to do |format|
      format.html # index.erb
      format.xml  { render :xml => @<%= table_name %> }
    end
  end

...

It looks like the resource generator generates the exact same thing as the scaffold generator with the exception that it generates an empty controller rather than a scaffold controller.

So the moral of the story is, use the scaffold generator if you want to generate a resource and a scaffold (i.e., you're a beginner); use the resource generator if you're an expert and you don't want the scaffold part...

[edit] How do I continue using scaffold_resource if I really want to use it still?

Well, you could just content yourself with staying at 6631 for the rest of your like, like this:

> rake rails:freeze:edge REVISION=6631

But I, for one, would prefer not to be tied down to an old version. So (as of this writing), I'm frozen to 7200 but I've exported the code that was removed in 6632, like this:

> svn export -r 6631 http://dev.rubyonrails.org/svn/rails/trunk/railties/lib/rails_generator/generators/components/scaffold_resource/@6631 vendor/rails/railties/lib/rails_generator/generators/components/scaffold_resource/

> svn add vendor/rails/railties/lib/rails_generator/generators/components/scaffold_resource

> svn ci vendor/rails/railties/lib/rails_generator/generators/components/scaffold_resource -m 'Added scaffold_resource back in, from r6631'

[edit] resource generator

 > ./script/generate resource User username:string group_id:integer
      exists  app/models/
      exists  app/controllers/
      exists  app/helpers/
      create  app/views/users
      exists  test/functional/
      exists  test/unit/
  dependency  model
      exists    app/models/
      exists    test/unit/
      exists    test/fixtures/
   identical    app/models/user.rb
   identical    test/unit/user_test.rb
      create    test/fixtures/users.yml
      exists    db/migrate
      create    db/migrate/001_create_users.rb
      create  app/controllers/users_controller.rb
      create  test/functional/users_controller_test.rb
      create  app/helpers/users_helper.rb
       route  map.resources :users

[edit] Peepcode

http://peepcode.com/products/restful-rails, $9

RESTful routes are a concept that will be a big part of the upcoming Rails 1.2, but they are also very confusing!

This screencast covers the basics of REST and walks through a simple application to show how REST routes work. You’ll learn about the magic that goes on behind the scenes and how you can design a REST application with confidence.

Routes, URLs, interface elements, template redirection, testing, and general tips are covered over the course of 85 minutes.

If you are already familiar with how to build a Rails application, this screencast will give you the knowledge you need to convert an existing application to REST or design a new app with the principles of REST.

[edit] Consuming restful resources

[edit] ActiveResource

> rake rails:freeze:edge

> ffind activeresource; ffind active_resource
(nothing)

 > ./script/about
/usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require': no such file to load -- active_resource (MissingSourceFile)
        from /usr/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `require'
        from /home/tyler/code/examples/restful_resource/vendor/rails/activerecord/lib/../../activesupport/lib/active_support/dependencies.rb:495:in `require'
        from /home/tyler/code/examples/restful_resource/vendor/rails/activerecord/lib/../../activesupport/lib/active_support/dependencies.rb:342:in `new_constants_in'
        from /home/tyler/code/examples/restful_resource/vendor/rails/activerecord/lib/../../activesupport/lib/active_support/dependencies.rb:495:in `require'
        from ./script/../config/../vendor/rails/railties/lib/initializer.rb:160:in `require_frameworks'
        from ./script/../config/../vendor/rails/railties/lib/initializer.rb:160:in `each'
        from ./script/../config/../vendor/rails/railties/lib/initializer.rb:160:in `require_frameworks'
        from ./script/../config/../vendor/rails/railties/lib/initializer.rb:88:in `process'
        from ./script/../config/../vendor/rails/railties/lib/initializer.rb:49:in `send'
        from ./script/../config/../vendor/rails/railties/lib/initializer.rb:49:in `run'
        from /home/tyler/code/examples/restful_resource/config/environment.rb:13
        from /home/tyler/code/examples/restful_resource/vendor/rails/railties/lib/commands/about.rb:1:in `require'
        from /home/tyler/code/examples/restful_resource/vendor/rails/railties/lib/commands/about.rb:1
        from ./script/about:3:in `require'
        from ./script/about:3

> svn export http://dev.rubyonrails.org/svn/rails/trunk/activeresource vendor/rails/activeresource

> ffind activeresource; ffind active_resource
./vendor/rails/activeresource
./vendor/rails/activeresource/lib/active_resource.rb
./vendor/rails/activeresource/lib/active_resource

CREATE TABLE tasks ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, "name" varchar(255) DEFAULT NULL, "description" text DEFAULT NULL, "due_date" date DEFAULT NULL);

restful_resource_consumer > ./script/console
...

irb -> task.due_date = Time.now
    => Fri Jul 20 17:59:49 -0700 2007

irb -> task.save
    => true

irb -> task
    => #<Task:0xb7ce33a0 @prefix_options={}, @attributes={"name"=>"Mow the lawn", "id"=>2, "description"=>nil, "due_date"=>Sat, 21 Jul 2007}>

irb -> task = Task.find(2)
    => #<Task:0xb7c04984 @prefix_options={}, @attributes={"name"=>"Mow the lawn", "id"=>2, "description"=>nil, "due_date"=>Sat, 21 Jul 2007}>

restful_resource > ./script/console
irb -> Task.create(:due_date => Time.now)
    => #<Task id: 3, name: nil, description: nil, due_date: "2007-07-20 18:24:34">

irb -> Task.find(3)
    => #<Task id: 3, name: nil, description: nil, due_date: "2007-07-20">