Simple Config is a plugin designed to make application-wide configuration settings easy to set and access in an object-oriented fashion.

This library was originally designed to be a Rails plugin, but it's now a standard Ruby library with no dependency on Rails. You can use it in any Ruby application or project.

Rails Configuration vs SimpleConfig

Rails already provides a way of configuring the framework on a per-environment or application basis, but the more the application becomes complex, the more the feature shows its limit.

One common solution is to put your app configuration into YAML files and load them somewhere in your environment, but when you have many developers and dynamic configurations this is not always the best choice.

Compared to the default Rails configuration system, SimpleConfig provides the following additional features:

• Ability to define per developer settings using the

  local.rb

  file
• Ability to nest configurations in groups
• Ability to clone configs
• Ability to load unlimited configuration scripts

Getting started

The plugin comes with a rake task to get you up and running quickly, so start by running that.

$ rake simpleconfig:setup

This will create a

config/settings

config/initializers/configuration.rb

Now, if you open up the

configuration.rb

SimpleConfig.for :application do

your app configuration here
  load File.join(Rails.root, "config", "settings", "application.rb"),   :if_exists? => true
  load File.join(Rails.root, "config", "settings", "#{RAILS_ENV}.rb"),  :if_exists? => true
  load File.join(Rails.root, "config", "settings", "local.rb"),         :if_exists? => true
end

This is where you can set any configuration variables that are required across all Rails environments. The

load

SimpleConfig.for

:if_exists?

Variables can be overwritten, and are defined in the order that they are loaded, so you can set up default values in the above file and override them in the environment files.

As well as loading a settings file for your current Rails environment, a file called "local.rb" is loaded which is designed as a place for you to override variables specific to your own development environment -- you can just keep a copy of this locally without having to check it into your version control system[1].

Variables

Setting Variables

Setting variables is simple and will be familiar to anybody who has used Capistrano. Whether in your main

SimpleConfig.for

set

SimpleConfig.for :application do
  set :my_variable, 'hello world'
end

SimpleConfig also supports a form of namespacing that allows you to group logical sets of variables together:

SimpleConfig.for :application do
  group :awesome_stuff do
    set :my_variable, 'hello world'
  end
end

Both the

set

load

group

Whilst I'd recommend not nesting your groups more than one-level, there is no limit on how deep they can be nested.

Unsetting variables

Sometimes you might want to completely delete a variable from the collection. Simply setting its value to nil doesn't work because

nil

unset

SimpleConfig.for :application do
  set :my_variable, 'hello world'

  ...
  unset :my_variable
end

For instance, this is useful to remove global settings at environment level instead of overwriting the default value with a nonsense-one.

unset

Does a specific variable exist?

I don't know but you can check it yourself using

exists?

config = SimpleConfig.for(:application) do
  set :my_variable, 'hello world'
end

write some nice code
config.exists? :my_variable     # => true
config.exists? :your_variable   # => false

Accessing your configuration

SimpleConfig allows you set as many separate configurations as you like using the

SimpleConfig.for

SimpleConfig.for

It is worth pointing out that

SimpleConfig.for

SimpleConfig.for

Once you have a reference to your configuration object, you can access variables using method access. Given the above example,

:my_variable

config = SimpleConfig.for(:application)
config.my_variable # => "hello world"

Accessing grouped variables works as you would expect:

config = SimpleConfig.for(:application)
config.awesome_stuff.my_variable # => "hello world"

Using your configuration in your Rails app

When the application is initalized, by default the configurations are stored in the

:application

SimpleConfig.for(:application)

It's a common habit to define a

config

module Configurable
  def config
    SimpleConfig.for(:application)
  end
end

class ApplicationController < ActionController::Base
  extend  Configurable
  include Configurable
  def do_something
    # here you can use config
    if config.my_variable 
      render :foo
    end
      render :bar
    else
  end
end

An other very common pattern is to assing your configuration object to a constant so that it becomes globally available in your Rails project.

# config/initializers/configuration.rb
# after the initialization block
CONFIG = SimpleConfig.for :app

Then anywhere in your app

def do_something
  if CONFIG.my_variable 
    render :foo
  end
    render :bar
  else
end

fn1(footnote). In fact, I recommend you make sure your version control system ignores this file otherwise you risk checking in a file that will override values in production!