Some handy I18nization for my ApplicationDecorator

application_decorator.rb

class ApplicationDecorator < Draper::Base

  # By default, humanize the attributes listed.
  #
  # Example:
  #
  #   # user_decorator.rb
  #   class UserDecorator < ApplicationDecorator
  #     decorates :user
  #     humanizes :activation_status, :plan_status
  #   end
  #
  # See +ApplicationDecorator#humanize+ for a more detailed example.
  def self.humanizes(*attrs)
    attrs.each do |attr|
      define_method attr do
        humanize attr
      end
    end
  end

  # Humanize an attribute using I18n, falling back to the humanized attributes value.
  #
  # Example:
  #
  #   # user_decorator.rb
  #   class UserDecorator < ApplicationDecorator
  #     decorates :user
  #
  #     def activation_status
  #       humanize :activation_status
  #     end
  #
  #     def plan_status
  #       humanize :plan_status
  #     end
  #   end
  #
  #   # en.yml
  #   en:
  #     active: Current
  #     user:
  #       activation_status:
  #         active: 'Activated'
  #
  #   # Examples:
  #   @user.activation_status = 'active';
  #   @user.decorator.activation_status # => 'Activated'
  #
  #   @user.plan_status = 'active'
  #   @user.decorator.plan_status # => 'Current'
  #
  #   @user.activation_status = 'inactive'
  #   @user.decorator.activation_status = 'Inactive'
  def humanize(attribute, key = model.send(attribute), default = key.to_s.humanize)
    i18n_with_scoped_defaults key, [self.class.model_name.i18n_key, attribute], default
  end

  # Try to translate a key with I18n and a scope but fallback to less-and-less scope.
  # An example will explain more clearly:
  #
  #   i18n_with_scoped_defaults(:some_key, [:foo, :bar, :baz])
  #
  # Will try the following I18n translations in order:
  # * foo.bar.baz.some_key
  # * foo.bar.some_key
  # * foo.some_key
  # * some_key
  #
  # And if none of the I18n keys translate, it will use the default param (which defaults to
  # humanizing the provided key).
  #
  def i18n_with_scoped_defaults(key, scope = [], default = key.to_s.humanize)
    scope << key
    key = scope.join('.').to_sym

    defaults = []
    defaults << scope.join('.').to_sym while scope.delete_at(-2)
    defaults << default

    I18n.t key, default: defaults
  end

end