ComposedValidations

This gem's purpose is to get around having to set validations on your base ActiveModel::Model class. Have you ever wanted to conditionally set validations based on business logic? Maybe this gem will help.

Add this line to your application's Gemfile:

gem 'composed_validations'

And then execute:

$ bundle

Or install it yourself as:

$ gem install composed_validations

This gem works on the premise of a few simple interfaces:

There's an object which responds to the #valid? method, as used by ActiveModel::Validations, that you'd like to decorate functionality on to which has a set of accessible properties.

class MyObject
  include ActiveModel::Validations
  attr_accessor :title, :description
end

Validators are objects which takes the result of using a property accessor and says whether or not it's valid. It responds to valid_value?(value) and message(the message which gets added to errors if this is not valid.)

class StringIsBob
  def valid_value?(value)
    value.to_s == "Bob"
  end

  def message
    "needs to be the string 'Bob'"
  end
end

You can add these validations to an object with the following:

m = MyObject.new
m = ComposedValidators::WithValidatedProperty.new(m, :title, StringIsBob.new)
m.valid? # => false
m.title = "Bob"
m.valid? # => true

If you need to decorate multiple validators onto one property or multiple properties at once there is the DecorateProperties object. It works as follows:

m = MyObject.new
m = ComposedValidators::DecorateProperties.new(m, {:title => StringIsBob.new,
:description => StringIsBob.new})
m.valid? # => false
m.title = "Bob"
m.valid? # => false
m.description = "Bob"
m.valid? # => true

Sometimes you want a property to be valid if one or more validations are true, rather than all. To accomplish this we've provided an OrValidator composite object. It can be used as follows:

m = Myobject.new
composed_validator = ComposedValidators::OrValidator.new([StringIsBob.new,
StringIsJoe.new])
m = ComposedValidators::WithValidatedProperty.new(m, :title, composed_validator)
m.valid? # => false
m.title = "Bob"
m.valid? # => true
m.title = "Joe"
m.valid? # => true

1. Fork it ( https://github.com/[my-github-username]/composed_validations/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request