app-models-setting.rb

class Setting
  include Mongoid::Document
  include Mongoid::Timestamps

  include Mongoid::History::Trackable
  track_history track_create: false,
    track_update: true,
    track_destroy: true

  cattr_accessor :succeeds
  @@succeeds = false

  cattr_accessor :settings
  @@settings = nil

  field :internal, type: String
  field :cast, type: String
  field :description, type: String, localize: true
  field :content, type: String, localize: true

  scope :ordered, lambda {
    order_by(:internal, :asc)
  }

  validates :internal, presence: true, uniqueness: true
  validates :cast, :description, :content, presence: true

  class << self
    def [](internal)
      load!

      if @@settings[internal.to_s]
        @@settings[internal]
      else
        nil
      end
    end

    def load!
      return if succeeds and not @@settings.nil?
      file = Rails.root.join('config', 'application.yml')

      @@settings = {}

      if File.exists? file
        yaml = YAML.load(open(file)).to_hash

        @@settings.deep_merge! yaml['defaults']
        @@settings.deep_merge! yaml[Rails.env]
      end

      if self.exists?
        self.all.each do |setting|
          content = case setting.cast
            when 'boolean'
              !!setting.content
            when 'array'
              setting.content.split ','
            else
              setting.content
          end

          setting.internal.split('.').tap do |ks|
            ks[0...-1].inject(@@settings) { |s, k| s[k] ||= { } }[ks[-1]] = content
          end
        end

        @@succeeds = true
      end
    end
  end
end

config-application.yml

defaults:
  mailer:
    from: 'Foo <[email protected]>'
    method: 'smtp'
    smtp:
      address: 'smtp.gmail.com'
      port: 587
      domain: 'foo.de'
      user_name: '[email protected]'
      password: 'foofoo'
      authentication: 'plain'
      enable_starttls_auto: true
    default:
      mime_version: '1.0'
      charset: 'UTF-8'
      content_type: 'text/plain'
      parts_order:
        - 'text/html'
        - 'text/plain'
        - 'text/enriched'
    url:
      host: 'localhost:3000'
      protocol: 'http://'

  images:
    asset_host: 'localhost:3000'

  assets:
    asset_host: 'localhost:3000'

development:
  foo: 'bar'

test:
  foo: 'bar'

production:
  mailer:
    url:
      host: 'www.foo.de'
      protocol: 'https://'

  images:
    asset_host: 'images.foo.de'

  assets:
    asset_host: 'assets.foo.de'