ActiveRecord partial validations

ActiveRecord support for partial validations which allows you to validate only the attributes that are present at the time you're validating a model.

Just add using_partial_validations to your model and you're good to go :)

E.g.:

class Person < ActiveRecord::Base 
  using_partial_validations

  validates_inclussion_of :name, :in => ["Dario", "Javier", "Cravero"]
end

will only validate the name if the model has it when it's been created, therefore:

p=Person.create
p.valid? # true
p.name="John"
p.valid? # false
p.valid? "Dario" # true

At @starlightlabs we've found this to be the cleanest solution to submitting complex-multi-step-forms for one model. We've tried adding a steps variable to the models and stuff like that but it just feels dirty and it actually mixes up stuff which, in our consideration, shouldn't be mixed -i.e. views & models. Let us know if you've found this useful or have any other solution. :)