class Foo < ActiveRecord::Base

  # validate that attribute :bar is a String
  validates_type :bar, :string

  # validate that attribute :baz is an Integer with a custom error message
  validates_type :baz, :integer, message: 'Baz must be an Integer'

  # validate that attribute :qux is an Array, allow blank
  validates_type :qux, :array, allow_blank: true

  # validate that attribute :whatever is a Boolean
  validates_type :whatever, :boolean

  # validate that attribute :thing is a Float or nil
  validates_type :thing, :float, allow_nil: true

  # validate that attribute :when is a Time
  validates_type :when, :time

  # validate that attribute :birthday is a Date or blank
  validates_type :birthday, :date, allow_blank: true

  # validate that attribute :fox is of type Custom
  validates_type :fox, Custom
end

class Bar
  include ActiveModel::Validations

  attr_accessor :foo, :qux

  validates_type :foo, :string

  # Custom error message support
  validates_type :qux, :boolean, message: 'Attribute qux must be a boolean!'
end

class Banana < ActiveRecord::Base

  # The banana's peel attribute must be a string
  validates :peel, type: { type: :string }

  # Custom error message for ripeness of banana
  validates :ripe, type: { type: :boolean, message: 'Only ripe bananas allowed' }
end

class Foo < ActiveRecord::Base
  # validate that attribute :baz is an Integer with a custom error message
  #   only if :conditional_method evaluates to true
  validates_type :baz, :integer, message: 'Baz must be an Integer', if: :conditional_method

  def conditional_method
    # some kind of logic that is important to pass
  end

  # validate that attribute :baz is a Float and is included in a specific array
  validates_type :foo, :float, in: [1.0, 2.5, 3.0]
end