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)