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 to be able to have activerecord type validations in each command class so that after it is run the results are automatically tested against all the "validations". However, I am not sure how to do this. My code looks like this (simplified to show the important parts).

class CodesecureCommand
  def execute
    result = RestClient.post("http://#{codesecure.host_name_port}#{path}", post_data)

    return parse(result) #parse simple returns a Hpricot document
  end
end

class RunScan < CodesecureCommand

  #What I have now
  #I have to override the execute function so that it calls the local success method
  #to see if it failed or not.
  def execute()
    result = super()

    if success(result)
      return true
    else
    end

  end

  def success(result)
    result.search('div.transaction-message') do |message|
      if message.innerHTML.scan(/Configure abuse setting for domain users successfully\./).length == 1
        return true
      end
    end
  end



  #What I would like is to be able to call execute (without having to override it).
  #then after it runs it calls back to this class to check

  #if the regex matches the command was successful and returns true
  test_success /regex/

  #if test_success fails then these are called
  #the idea being that I can use the regex to identify errors that happened then
  #report them to the user
  identify_error /regex/, "message"
  identify_error /regex/, "message"
  end
end

What I want is that after the execute method is called the test_success and identify_error are automatically called like the validations in activerecord. Can anybody tell me how to do this? Thanks

Answer 1

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.

Answer 2

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