Blueprint Config

Blueprint Config is a gem which allows you to easily configure your Ruby applications in a multitude of ways.

It was highly inspired by other solutions, Econfig in first place.

Installation

Add this to your Gemfile:

gem "blueprint_config"

Using with Ruby on Rails app

In Rails, you'll want to add this in config/application.rb:

module MyApp
  class Application < Rails::Application
    BlueprintConfig.configure_rails(config)
  end
end

This will create module "AppConfig" for accessing configuration options, and load configuration in following order:

config/app.yml
credentials
ENV variables
settings in database
config/app.local.yml

Settings form database will be available only after rails app initialization. Everything else can be used in initializers.

Accessing configuration variables.

You can access configuration variables in any of followining ways:

Member access syntax:

irb(main):001> AppConfig.action_mailer.smtp_settings.address
=> "127.0.0.1"

If at some level variable is not defined and you try to access nested variable, you'll gen an exception

irb(main):001> AppConfig.some.var
(irb):1:in `<main>': undefined method `var' for nil:NilClass (NoMethodError)

AppConfig.some.var
              ^^^^

If nil is suitable as a default value tyou can use safe navigation operator

irb(main):001> AppConfig.some&.var
=> nil

Optionaly you use bang methods to allways raise exception when variable is not defined

irb(main):001> AppConfig.some
=> nil
irb(main):002> AppConfig.some!
(irb):2:in `<main>': Configuration key 'some' is not set (KeyError)
irb(main):003> AppConfig.some!.var!
(irb):3:in `<main>': Configuration key 'some' is not set (KeyError)

Or use question mark to check if variable is defined

irb(main):001> AppConfig.some?
=> false
irb(main):002> AppConfig.host?
=> true

Note: Because question mark methods return Boolean you cannot chain em.

Hash access syntax

You can use both symbols or strings as keys

irb(main):001> AppConfig[:action_mailer][:delivery_method]
=> :letter_opener
irb(main):002> AppConfig['action_mailer']['delivery_method']
=> :letter_opener

Again, if some level is missing you'll get an exception

irb(main):001> AppConfig[:some][:var]
(irb):1:in `<main>': undefined method `[]' for nil:NilClass (NoMethodError)

AppConfig[:some][:var]
                ^^^^^^

Fetch

You can use hash-style fetch method, but it works only for one level (but you can chain it). Default values as second parameter or block are supported. Without default value missing key will raise exception.

irb(main):001> AppConfig.fetch(:host)
=> "localhost"
irb(main):002> AppConfig.fetch(:var)
(irb):2:in `<main>': Configuration key 'var' is not set (KeyError)
irb(main):003> AppConfig.fetch(:var, 123)
=> 123
irb(main):004> AppConfig.fetch(:var){123}
=> 123

Dig

Dig permits to sefely get value in nested structures (including arrays)

irb(main):001> AppConfig.dig(:action_mailer, :smtp_settings, :address)
=> "127.0.0.1"
irb(main):002> AppConfig.dig(:action_mailer, :smtp_settings, :unknown)
=> nil

Bang version will raise exception when key at any level is missing

irb(main):001> AppConfig.dig!(:action_mailer, :smtp_settings, :unknown)
(irb):1:in `<main>': Configuration key 'action_mailer.smtp_settings.unknown' is not set (KeyError)
irb(main):002> AppConfig.dig!(:action, :smtp_settings, :address)
(irb):2:in `<main>': Configuration key 'action' is not set (KeyError)

Whenever possible exception message specifies which key is missing.

License

MIT, see separate LICENSE.txt file