aishek / nihilist

Nigilist Ruby gem — Null Object for User model in your app

Nigilist

Nigilist is extremely useful for implement Null Object pattern. It allows null object to return false for all question-methods, nil for all non-bang-methods, [] for all methods in plural form (and in Ruby on Rails null-relation for same name ActiveRecord model) without defining them.

Installation

gem install nigilist

Usage

class Order < ActiveRecord::Base
end

class Guest
  include Nigilist

  def polite?
    true
  end

  def locale
    'ru'
  end
end

current_user = Guest.new
current_user.admin?  # false — for all question methods
current_user.polite? # true — becase it is explicit defined
current_user.orders  # Order.none — for all plural methods because same singular name ActiveRecord model exists
current_user.planets # [] — for all plural methods without because singular name ActiveRecord model doesn't exists
current_user.address # nil — for all non question, non plural and non bang methods
current_user.locale  # 'ru' — becase it is explicit defined

Explanation of Null Object pattern

For example, you have a User model, with #admin? method, and Guest model allows you use same interface for both authorized and unauthorized users like so:

class Guest
  def admin?
    false
  end
end

current_user = current_session.user || Guest.new
current_user.admin?

So when your project grows and other methods got it place inside User model you have to define same methods in Guest model which contains no logic but only return false or nil. In that case Nigilist could be helpful.

License

Nigilist is free software, and may be redistributed under the MIT License.

Contributors

• Alexandr Borisov
• Ivan Nemytchenko

The gem about one method

The gem contains exactly one module with one method defined: method_missing. I'm sure you able to implement it by yourself in couple of minutes. So feel free just to copy it from lib/nihilist.rb 😉

nihilist's Issues

Return empty array for methods in plural form

like "users", "devices" etc

Provide a way to mimic AR associations

If you have associations in your original model, then in order to make your code work well with Null object you need to fo something like this:

class NullCompany
  include Nigilist

  def devices
    Device.none
  end
end

I am not sure if it makes sense to add this functionality, but at least it worth mentioning in Readme

Sync repo name and gem name

It is a bit confusing that gem name and repo names are different