ActiveRecord - replace model validation error with warning

Question

Hi,

I want to be able to replace a field error with a warning when saving/updating a model in rails. Basically I want to just write a wrapper around the validation methods that'll generate the error, save the model and perhaps be available in a warnings hash (which works just like the errors hash):

class Person < ActiveRecord::Base
  # normal validation
  validates_presence_of :name

  # validation with warning
  validates_numericality_of :age, 
                            :only_integer => true, 
                            :warning => true # <-- only warn
end

>>> p = Person.new(:name => 'john', :age => 2.2)
>>> p.save
=> true # <-- able to save to db
>>> p.warnings.map { |field, message| "#{field} - #{message}" }
["age - is not a number"] # <-- have access to warning content

Any idea how I could implement this? I was able to add :warning => false default value to ActiveRecord::Validations::ClassMethods::DEFAULT_VALIDATION_OPTIONS By extending the module, but I'm looking for some insight on how to implement the rest. Thanks.