roar-rails

Makes using Roar's representers in your Rails app fun.

Roar is a framework for parsing and rendering REST documents. For a better overview about representers please check the roar repository.

Features

• Rendering with responders
• Parsing incoming documents
• URL helpers in representers
• Better tests
• Autoloading

Rendering with #respond_with

roar-rails provides a number of baked-in rendering methods.

Conventional Rendering

Easily render resources using representers with the built-in responder.

class SingersController < ApplicationController
  include Roar::Rails::ControllerAdditions
  respond_to :json

  def show
    singer = Singer.find_by_id(params[:id])
    respond_with singer
  end
end

The representer name will be infered from the passed model class (e.g. a Singer instance gets the SingerRepresenter). If the passed model is a collection it will be extended using a representer. The representer name will be computed from the controller name (e.g. a SingersController uses the SingersRepresenter).

Need to use a representer with a different name than your model? You may always pass it in using the :represent_with option:

respond_with singers, :represent_with => MusicianCollectionRepresenter
end

Represents Configuration

If you don't want to use conventions or pass representers you can configure them on the class level using #represents. This will also call respond_to for you.

class SingersController < ApplicationController
  represents :json, Musician

This will use the MusicianRepresenter for models and MusiciansRepresenter for representing collections.

Note that #represents also allows fine-tuning.

class SingersController < ApplicationController
  represents :json, :entity => MusicianRepresenter, :collection => MusicianCollectionRepresenter

Old API Support

If you don't want to write a dedicated representer for a collection of items (highly recommended, thou) but rather use a representer for each item, use the :represent_items_with option.

class SingersController < ApplicationController

  def index
    singers = Musician.find(:all)
    respond_with singers, :represent_items_with => SingerRepresenter
  end
end

Goes great with Jose Valim's responders gem!

class SingersController < ApplicationController
  respond_to :json

  responders Roar::Rails::Responder

  def show
    singer = Singer.find_by_id(params[:id])
    respond_with singer
  end

end

Parsing incoming documents

In #create and #update actions it is often necessary to parse the incoming representation and map it to a model instance. Use the #consume! method for this.

class SingersController < ApplicationController
  respond_to :json

  def create
    singer = Singer.new
    consume!(singer)

    respond_with singer
  end
end

The consume! call will roughly do the following.

singer.
  extend(SingerRepresenter)
  from_json(request.body)

So, #consume! helps you figuring out the representer module and reading the incoming document.

Note that it respects settings from #represents. It uses the same mechanics known from #respond_with to choose a representer.

consume!(singer, :represent_with => MusicianRepresenter)

URL Helpers

Any URL helpers from the Rails app are automatically available in representers.

module FruitRepresenter
  include Roar::Representer::JSON
  include Roar::Representer::Feature::Hypermedia

  link :self do
    fruit_url self
  end
end

To get the hyperlinks up and running, please make sure to set the right host name in your environment files (config/environments):

config.representer.default_url_options = {:host => "127.0.0.1:3000"}

Attention: If you are using representers from a gem your Rails URL helpers might not work in these modules. This is due to a loading order problem in Rails. As a workaround, don't require the representers in the gem but load them as lately as possible, usually it works when you require in the controller. We are working on fixing that problem.

Testing

Autoloading

Put your representers in app/representers and they will be autoloaded by Rails. Also, frequently used modules as media representers and features don't need to be required manually.

Contributors

• Railslove and especially Michael Bumann [bumi] have heavily supported development of roar-rails ("resource :singers").