TL;DR This library is deprecated and will no longer be maintained. You should consider migrating to ActiveModel::Serializer.

Porth was a joy to create and use, but it's time to recognise when other libraries do it better. The principle idea behind Porth was to separate the JSON and XML representations of your models.

ActiveModel::Serializer is a better library with a tonne of support from the community. I would personally choose this for my next API.

Thank you for supporting Porth.

Write your views using plain old Ruby. Views are for representation, not defining #as_json in a model. There's no need to learn a DSL for building arrays and hashes. Just use Ruby. Views are written once and rendered in JSON(P) or XML based on the requested format. Porth makes few assumptions and can be configured.

Add this to your project's Gemfile and run $ bundle install

gem 'porth'

Create a controller that responds to JSON, XML or both.

# app/controllers/transmitters_controller.rb
class TransmittersController < ApplicationController
  respond_to :json, :xml
  
  def index
    @transmitters = Transmitter.all
    respond_with @transmitters
  end

  # ...
end

Create a template with a .rb extension. Write plain old Ruby. Objects must respond to #to_json or #to_xml. Arrays and hashes are best.

# app/views/transmitters/index.rb
@transmitters.map do |t|
  {
    name: t.area_served,
    latitude: t.latitude,
    longitude: t.longitude,
    nearby: t.nearby.size
  }
end

GET /transmitters.json

[{"name":"Brisbane","latitude":-27.4661111111111,"longitude":152.946388888889,"nearby":11}]

GET /transmitters.json?callback=myFunction

myFunction([{"name":"Brisbane","latitude":-27.4661111111111,"longitude":152.946388888889,"nearby":11}])

GET /transmitters.xml

<?xml version="1.0" encoding="UTF-8"?>
<transmitters type="array">
  <transmitter>
    <name>Brisbane</name>
    <latitude type="float">-27.4661111111111</latitude>
    <longitude type="float">152.946388888889</longitude>
    <nearby type="integer">11</nearby>
  </transmitter>
</transmitters>

Porth::UnknownFormatError is raised when the requested format is not supported.

Porth calls #json_callback to get the function name for JSONP responses. By default this method is added to ActionController::Base and returns params[:callback]. Override #json_callback to get different behaviour.

class ApplicationController < ActionController::Base
  # ...

  protected
  
  def json_callback
    nil # Ignore JSONP requests
  end
end

Porth guesses the resource's name from the controller's class. Foo::BarsController becomes bars. Override #xml_root to explicitly set the resource name.

class TransmittersController < ApplicationController
  # ...

  protected
  
  def xml_root
    'sites'
  end
end

Resource names are pluralized or singularized by introspecting the return type from the view. Following convention, collection actions (index) should return an array of objects and member actions (new, create, edit, update, delete) should return an object. Override #xml_pluralized_root to explicitly set the collection resource name and override #xml_singularize_root to explicitly set the member resource name.

class SeaFoodsController < ApplicationController
  # ...

  protected
  
  def xml_pluralized_root
    'fish'
  end
          
  def xml_singularized_root
    'fish'
  end
end

Remember, anything you can do in Ruby you can do in Porth. Here are a few ideas for writing and testing your views.

Conveniently select a subset of attributes.

# app/views/users/show.rb
@author.attributes.slice 'id', 'first_name', 'last_name', 'email'

Hashes may get dirty if you attempt to build them all in one go. Consider storing the hash in a variable and adding to it based on a condition. Like a method you need to return the hash on the last line.

# app/views/users/show.rb
attributes = @author.attributes.slice 'id', 'first_name', 'last_name', 'email'
if current_user.admin?
  attributes['ip_address'] = @author.ip_address
  attributes['likability'] = @author.determine_likability_as_of Time.current
end
attributes

Use functional tests to verify the response's body is correct.

# app/views/posts/show.rb
@author.attributes.slice 'id', 'title', 'body'

JSON maps well to Ruby's hashes. Set the response to JSON, parse the body into a hash and verify the key-value pairs.

# test/functional/posts_controller_test.rb
require 'test_helper'

class PostsControllerTest < ActionController::TestCase
  # ...
  
  test "GET show" do
    get :show, id: posts(:hello_word).id, format: 'json'
    post = JSON.parse response.body
    assert_equal 123040040, post['id']
    assert_equal 'Hello, World!', post['title']
    assert_equal 'Lorem ipsum dolar sit amet...', post['body']
  end
end

• MRI 1.8.7
• MRI 1.9.2+
• JRuby 1.6.4+

• ActionPack 3.0.0+

• porth-plist - Adds Property list (.plist) support

1. Fork
2. Install dependancies by running $ bundle install
3. Write tests and code
4. Make sure the tests pass by running $ bundle exec rake
5. Push and send a pull request on GitHub

Porth is the result of numerous discussions at Everyday Hero around better API design.

Copyright © 2011 Tate Johnson. Released under the MIT license. See LICENSE.