I have just had my sexy validations patch accepted into Rails. Much thanks to José Valim for helping me get this applied.
The reason for the name “sexy validations” is that it gives a much more concise way of defining validation and reusing custom validator classes. Much like what sexy migrations did for defining your database schema.
Simple example of using existing Rails validations, the “sexy” way:
class Film < ActiveRecord::Base
validates :title, :presence => true, :uniqueness => true, :length => { :maximum => 100 }
validates :budget, :presence => true, :length => { :within => 1..10000000 }
end
The power of the “validates” method comes though, when using in conjunction with custom validators:
class IntenseFilmTitleValidator < ActiveModel::EachValidator
def validate_each(record, attribute, value)
record.errors[attribute] << "must start with 'The'" unless value =~ /^The/
end
end
class SpendValidator < ActiveModel::EachValidator
def validate_each(record, attribute, value)
spend = case options[:size]
when :big then 100000000
when :small then 100000
end
record.errors[attribute] << "must not exceed #{spend}" if value > spend
end
end
class Film < ActiveRecord::Base
validates :title, :presence => true, :intense_film_title => true
validates :budget, :spend => { :size => :big } # using custom options
end
All validations in Rails, along with other common model functionality have been extracted into ActiveModel, so you can also use validations and Validator classes without ActiveRecord e.g.
class EmailValidator < ActiveModel::EachValidator
def validate_each(record, attribute, value)
record.errors[attribute] << (options[:message] || "is not an email") unless
value =~ /^([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})$/i
end
end
class Person
include ActiveModel::Validations
attr_accessor :name, :email
validates :name, :presence => true, :length => { :maximum => 100 }
validates :email, :presence => true, :email => true
end
Have fun!