WhyValidationsSuckIn96

Description

WhyValidationsSuckIn96 is a library for adding validation support to objects. It aims to have a very minimal ‘surface area’, API-wise, and to be as easily testable as possible. It has no external dependencies unless you wish to use the ActiveRecord integration, in which case you clearly need ActiveRecord installed.

Documentation

See ‘doc/index.html’ for details, or check the GitHub Pages site for the project.

Install

gem install ‘whyvalidationssuckin96’

Basic Usage

Require ‘whyvalidationssuckin96’ and include the WhyValidationsSuckIn96::ValidationSupport module into your class:

require 'whyvalidationssuckin96'

class Song
  attr_accessor :title, :artist
  include WhyValidationsSuckIn96::ValidationSupport
end

Define your validations or call pre-existing validation macros inside a validation setup block:

require 'whyvalidationssuckin96'

class Song
  attr_accessor :title, :artist, :year
  include WhyValidationsSuckIn96::ValidationSupport
  
  setup_validations do
    validate :no_eighties_crap do
      if %w[BonJovi Dokken].include?(validatable.artist)
        fail
      else
        pass
      end
    end
    
    validates_presence_of :title, :artist
    validates_numericality_of :year, :only_integer => true
  end
end

Check instances of your class for validity and inspect the failed validations:

song = Song.new
song.valid?
song.invalid?
song.failed_validations
song.passed_validations
song.all_validations

Easily inspect and test for the presence of validations on your class:

Song.validation_collection.detect do |(klass, opts)|
  klass == WhyValidationsSuckIn96::ValidatesPresence
end

Song.validation_collection.detect do |(klass, opts)|
  klass == WhyValidationsSuckIn96::ValidatesNumericality && opts[:only_integer]
end

Create your own reusable and testable validations:

require 'whyvalidationssuckin96/skippable_validation'
require 'whyvalidationssuckin96/attribute_based_validation'

class ValidatesPrimaryColour < WhyValidationsSuckIn96::Validation
  include WhyValidationsSuckIn96::SkippableValidation
  include WhyValidationsSuckIn96::AttributeBasedValidation

  DefaultOptions = {:message => "is not a valid color"}
  ValidColours = %w[red green blue]
  
  def validate
    super
    if ValidColours.include?(attribute_value)
      pass
    else
      fail
    end
  end
  
end # ValidatesPrimaryColour

WhyValidationsSuckIn96::ValidationBuilder.register_macro :validates_primary_colour_of, ValidatesPrimaryColour

ActiveRecord Integration

WhyValidationsSuckIn96 features ActiveRecord support. The caveat is that it violently tears out the existing validation API so anything that uses that will break. The good news is that what it replaces the existing validation code with works as expected with features such as callbacks and preventing saves to the database when objects are invalid. All the standard ActiveRecord validation macros are available, and most have the same API to use when setting them up.

To use the ActiveRecord support:

require 'whyvalidationssuckin96/rails/active_record'

Then you can define validations as expected in your model classes:

class Song < ActiveRecord::Base
  setup_validations do
    validates_uniqueness_of :title, :scope => :artist
  end  
end

Contributing

Fork the project.
Make your feature addition or bug fix.
Add tests for it. This is important so I don’t break it in a future version unintentionally.
Commit, do not mess with Rakefile or VERSION. (if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull)
Send me a pull request.

Todo

Investigate moving to a model where single instances of validations are created and passed the object to validate, rather than the per-object validation scheme right now which may be a bottleneck.