Roar 0.10 with JSON-HAL Support and Representable 1.1.6 Released

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Just a quick round-up for new things in the “Roar”:https://github.com/apotonick/roar world. Here we go!

h3. Roar Speaks JSON-HAL Now!

In the last “Ruby on REST post”:http://nicksda.apotomo.de/2012/03/ruby-on-rest-5-learn-hypermedia-by-making-fruit-salad/ I explained the basics of the hypermedia type “HAL”:http://stateless.co/hal_specification.html which *gives your document nesting and linking* semantics. This promising format is now supported by Roar.

By including the @Representer::JSON::HAL@ module in your representer it will render and parse documents according to the HAL standard.

module OrderRepresenter
  include Roar::Representer::JSON::HAL
     
  property :id
  collection :items,
    :class => Item, 
    :extend => ItemRepresenter,
    :embedded => true

  link :self do "http://orders/#{id}" end
end

Links will now be pushed into the @_links@ property. Also note the new @:embedded@ option which will key the nested property under @_embedded@. And all that just by including a module – that’s the power of representers.

h3. Better Links in JSON

“Some users asked”:https://github.com/apotonick/roar/issues/15 for another link format when _not_ using the HAL representer. Usually links are handled like this.

"links":[
  { "rel":  "self", 
    "href": "http://orders/42"},
  { "rel":  "items", 
    "href": "http://orders/42/items"}
]}

This is just a format I came up with when writing Roar. Now, if you include @Representer::JSON::HAL::Links@ in your representer, links will be rendered and parsed a bit different.

"links": { 
  "self":  {"href": "http://orders/42"}, 
  "items": {"href": "http://orders/42/items"}
}

Here, @links@ is a hash keyed by @rel@ – very handy on the client side.

Also, you can now include more attributes in links.

link :rel => :self, :title => "That's me!"

Just provide a hash listing the attributes.

h3. Representable Got Conditional Properties!

Last but not least, “representable”:https://github.com/apotonick/representable, the underlying mapping gem of Roar got a new option in the 1.1.6 release. @:if@ allows you to define blocks that are evaled when parsing or rendering (“representing”, yo!) the object. If the proc returns false, the property is ignored.

property :state, :if => lambda { authorized? }

The block is executed in instance context allowing you to access instance methods and whatever else you need. Go for it!
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