ActiveConfiguration

ActiveConfiguration is an engine that exposes a generic settings store to ActiveRecord models. Made for very configurable applications, it allows you to avoid implementing specific ways to store settings for each model that needs such a configuration. If your application isn't very configurable, ActiveConfiguration isn't what you want.

If you had a Category model that only had a configurable sort attribute, ActiveConfiguration would be overkill. Rather, you would just read and write values using a specific sort column and restrict the allowed values using something like validates_inclusion_of.

However, if your Category model was more flexible in its configuration, you may want a sort setting, a limit setting and multiple price_filter settings that can be configured by your end user. Without ActiveConfiguration, you would have to develop a way to store and validate these settings for this specific scenario. The sort and limit settings are simple but because price_filter can accept multiple rules, you'd have to set up an additional model. Still, this isn't really an issue when you're dealing with just a single configurable model. When you're dealing with many, things tend to get messy.

With ActiveConfiguration, all of your settings, even for price_filter, can be stored in a generic way. ActiveConfiguration provides a place to store settings for each of your models and even handles validation when you restrict the allowed values or format of an option.

The source for this engine is located at:

http://github.com/tsmango/active_configuration

Add the following to your Gemfile:

gem 'active_configuration'

Generate the migration for the settings table:

rails g active_configuration:install

Note: The table can be changed from settings to something else by specifying a config option in an initializer like:

# config/initializers/active_configuration.rb

Rails.configuration.active_configuration_table_name = 'active_configuration_settings'

Migrate your database:

rake db:migrate

class Category < ActiveRecord::Base
	configure do
		option :sort do
			default  'alphabetical'
			restrict 'alphabetical', 'manual'
		end
		
		option :limit do
			format 'fixnum'
		end
		
		option :price_filter do
			format    'float'
			modifiers 'eq', 'lt', 'gt', 'lte', 'gte'
			multiple  true
		end
	end
end

After installing ActiveConfiguration, the #configure block is available to every ActiveRecord model. If the #configure block is defined with a valid configuration, additional methods are made available on the model.

Given we have defined the Category class above, instances will now have a #settings method where settings can be read from and written to.

>> category = Category.create(:name => 'Vinyl Records')
=> #<Category id: 1, name: "Vinyl Records", created_at: "2011-08-03 15:46:11", updated_at: "2011-08-03 15:46:11">

?> category.settings
=> #<ActiveConfiguration::SettingManager:0x10e7d1950 @configurable=#<Category id: 1, name: "Vinyl Records", created_at: "2011-08-03 15:46:11", updated_at: "2011-08-03 15:46:11">>

?> category.settings[:sort]
=> {:value=>"alphabetical", :modifier=>nil}

?> category.settings[:sort][:value]
=> "alphabetical"

?> category.settings[:sort][:value] = 'manual'
=> "manual"

?> category.settings[:price_filter]
=> []

?> category.settings[:price_filter] = [{:modifier => 'gt', :value => 10.00}, {:modifier => 'lte', :value => 25.00}]
=> [{:value=>10.0, :modifier=>"gt"}, {:value=>25.0, :modifier=>"lte"}]

?> category.save
=> true

?> category.settings[:sort][:value]
=> "manual"

?> category.settings[:price_filter]
=> [{:value=>10.0, :modifier=>"gt"}, {:value=>25.0, :modifier=>"lte"}]

Note:

Settings are only committed after a save of the configurable model. If any validation errors should arise, the save on the model will return false and errors will be added to the model's errors collection.

The spec/ directory contains a skeleton Rails 3.0.0 application for testing purposes. All specs can be found in spec/spec/.

To run the specs, do the following from the root of active_configuration:

bundle install --path=vendor/bundles --binstubs
bin/rspec spec

Copyright © 2011 Thomas Mango, released under the MIT license.