URL for models in JSON Response

MyModel.rb

class MyModel
  attr_accessor :item_url

  def as_json(options={})
    {
      :url => item_url
    }.merge(self.attributes)
  end
end

SomeController.rb

class SomeController
  def some_action
    @items = MyModel.search( .... )

    render :json => @items.map {|x| x.item_url = url_for(x); x}
  end
end