Easy within

active_model_within.rb

# This allows developers to pass an Active Model object
# to within, check and uncheck. This is very useful when
# used with `content_tag_for` since `content_tag_for`
# generates an unique dom id for each object. With this
# module, we can write:
#
#    within comment do
#      click_link "Destroy"
#    end
#
# Or even better:
#
#    click_link_within comment, "Destroy"
#
# Enabling or disabling roles based on checkboxes is also easy:
#
#    check role
#
module ActiveModelWithin
  def within(*args)
    object, prefix = args

    scope = if object.respond_to?(:to_model)
      ['#' + ActionController::RecordIdentifier.dom_id(object, prefix)]
    else
      args
    end

    super(*scope)
  end

  def click_link_within(scope, link)
    within(scope) { click_link(link) }
  end

  %w(check uncheck).each do |method|
    class_eval <<-RUBY, __FILE__, __LINE__ + 1
      def #{method}(*args)
        if args[0].respond_to?(:to_model)
          scope = ActionController::RecordIdentifier.dom_id(args[0], args[1])
          super(scope)
        else
          super
        end
      end
    RUBY
  end
end