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.

Installation

Add this line to your application's Gemfile:

gem 'composed_validations'

And then execute:

$ bundle

Or install it yourself as:

$ gem install composed_validations

Usage

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

Decorated Object

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

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) and message(the message which gets added to errors if this is not valid.)

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

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

Decorating One Property

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

Decorating Multiple Properties

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

OR Validations

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

Contributing

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