Module to allow validation of ActiveResource objects, which creates an Errors instance for every resource. Methods are implemented by overriding +Base#validate+ or its variants Each of these methods can inspect the state of the object, which usually means ensuring that a number of attributes have a certain value (such as not empty, within a given range, matching a certain regular expression and so on).

Example

  class Person < ActiveResource::Base
     self.site = "http://www.localhost.com:3000/"
     protected
       def validate
         errors.add_on_empty %w( first_name last_name )
         errors.add("phone_number", "has invalid format") unless phone_number =~ /[0-9]*/
       end

       def validate_on_create # is only run the first time a new object is saved
         unless valid_member?(self)
           errors.add("membership_discount", "has expired")
         end
       end

       def validate_on_update
         errors.add_to_base("No changes have occurred") if unchanged_attributes?
       end
  end

  person = Person.new("first_name" => "Jim", "phone_number" => "I will not tell you.")
  person.save                         # => false (and doesn't do the save)
  person.errors.empty?                # => false
  person.errors.count                 # => 2
  person.errors.on "last_name"        # => "can't be empty"
  person.attributes = { "last_name" => "Halpert", "phone_number" => "555-5555" }
  person.save                         # => true (and person is now saved to the remote service)