How to create activerecord style validations outside of activerecord?

Question

I am working on a testing framework for the software that my company writes. Our product is web based and After I run a RESTful request I want to process the results. I want t

Answer 1

Without having looked much at your code, here's my take on implementing validation class methods:

module Validations
  def self.included(base)
    base.extend ClassMethods
  end

  def validate
    errors.clear
    self.class.validations.each {|validation| validation.call(self) }
  end

  def valid?
    validate
    errors.blank?
  end

  def errors
    @errors ||= {}
  end

  module ClassMethods
    def validations
      @validations ||= []
    end

    def validates_presence_of(*attributes)
      validates_attributes(*attributes) do |instance, attribute, value, options|
        instance.errors[attribute] = "cant't be blank" if value.blank?
      end
    end

    def validates_format_of(*attributes)
      validates_attributes(*attributes) do |instance, attribute, value, options|
        instance.errors[attribute] = "is invalid" unless value =~ options[:with]
      end
    end

    def validates_attributes(*attributes, &proc)
      options = attributes.extract_options!

      validations << Proc.new { |instance|
        attributes.each {|attribute|
          proc.call(instance, attribute, instance.__send__(attribute), options)
        }
      }
    end
  end
end

It assumes that ActiveSupport is around, which it is in a Rails environment. You might want to extend it to allow multiple errors per attribute, with instance.errors[attribute] << "the message", but I left out obscurities like that in order to keep this short sample as simple as possible.

Here's a short usage example:

class MyClass
  include Validations

  attr_accessor :foo
  validates_presence_of :foo
  validates_format_of :foo, :with => /^[a-z]+$/
end

a = MyClass.new
puts a.valid?
# => false

a.foo = "letters"
puts a.valid?
# => true

a.foo = "Oh crap$(!)*#"
puts a.valid?
# => false

Answer 2

You want Validatable: sudo gem install validatable

class Person
  include Validatable
  validates_presence_of :name
  attr_accessor :name
end

Also, Validatable does not have a dependency on ActiveSupport.