Validation

Validation

Arkenstone provides some basic model validations and allows you to create custom ones as well. To enable validations in your class, include the Arkenstone::Validation module and then add validation directives in the class definition. Arkenstone Validations can even be used on non-Arkenstone classes.

class Widget
  include Arkenstone::Document
  include Arkenstone::Validation
  
  url 'http://example.com/widgets'
  
  attributes :name, :size, :sku
  
  validates :name, presence: true
end

class Ball
  include Arkenstone::Validation
  
  attr_accessor :radius
  
  validates :radius, presence: true
end

The Arkenstone::Validation module adds a bunch of instance and class methods to the including class. This allows you to check if an object is valid or not.

widg = Widget.new
widg.valid? # false, since a name is required
widg.name = 'Framistat'
widg.valid? # true

Pre-baked Validators

Arkenstone comes with a few common validators already built-in. All validators take an options hash as an optional parameter. This allows you to customize the error message it returns.

validates :name, presence: true, message: 'No really, you need a name'

presence

This validator will fail if the supplied property does not exist, if its value is nil, or if it is an empty string.

empty

Similar to presence, but geard towards Strings. Will fail if the value is nil or empty.

acceptance

This validator will fail if the supplied property does match the value specified by the directive.

validates :accept_t_and_c, acceptance: true
validates :is_assassin, acceptance: false

type

Checks if the property is a specific type. This uses is_a? to check, so subclasses will pass.

validates :name, type: String

format

Checks if the property's value matches the supplied regex. It is recommended that you provide a custom message here since Arkenstone can't read your mind about what this regex is testing.

validates :number_of_fleas, format: { with: /\d+/, message: "Must be a number." }

confirmation

This validator checks that the value of the property matches one that follows the supplied one with a _confirmation.

attr_accessor :password, :password_confirmation

validates :password, confirmation: true

widg.password = 'swordfish'
widg.password_confirmation = 'hunter2'
widg.valid? # false
widg.password = 'hunter2'
widg.valid? # true

Custom validations

If those don't cover all of your bases, you can create custom validation methods for your classes.

class Widget
  include Arkenstone::Document
  include Arkenstone::Validation
  
  url 'http://example.com/widgets'
  
  attributes :number
  
  validate :numberwang
  
  def numberwang
    errors.add(:number, "That's numberwang!") unless [3, 19, 333].include? @number
  end
end

When validations are run, the numberwang method will be called. If your custom check fails, call errors.add and supply a property name and error message.

valid? or validate

An object that includes the Arkenstone::Validation module can check its validation by calling validate or valid?. The former just runs all the validation method, the latter does as well, and then returns a boolean if there were no errors.