An easy way to implement HAL+JSON in Rails

_links.json.jbuilder

# app/views/partials/_links.json.jbuilder

json._links do
  if object.is_a?(ActiveRecord::Relation)
    json.self do
      json.href url_for(object.klass)
    end
  else
    json.self do
      json.href url_for(object)
    end
  end

  keys = []
  keys << :elements if object.is_a?(Enumerable)
  keys += object.class.reflections.keys.map(&:to_sym) if object.is_a?(ActiveRecord::Base)

  keys.each do |k|
    json.set! k do
      associations = :elements == k ? object : object.send(k)
      if associations.is_a?(Enumerable)
        json.array! associations do |association|
          json.href url_for(association)
        end
      else
        json.href url_for(associations)
      end
    end
  end
end

show.json.jbuilder

# app/views/actors/show.json.jbuilder

json.(@actor, :name)

json.partial! 'partials/links', object: @actor