a patch to get jbuilder to work with active_decorator on Rails.

jbuilder_extension.rb

# lib/jbuilder_ext/object_methods.rb
module JbuilderExt
  module ObjectMethods
    def __class__
      (class << self; self; end).superclass
    end

    def is_a?(klass)
      klass == __class__
    end
  end
end

# config/initialisers/view_template_extensions.rb
JbuilderTemplate.send(:include, JbuilderExt::ObjectMethods)