SEXY VALIDATION IN EDGE RAILS (RAILS 3) Rails 3中的sexy validation

名字定为“sexy validations” 的原因是:此种方法提供了1种更简洁的校验方式和重用已有的验证类.此种处理方式与 sexy migrations的工作方式类似.

使用已存在Rails校验的简单例子,如下:

class Film <; ActiveRecord::Base
  validates :title, :presence => true, :uniqueness => true, :length => { :maximum => 100 }
  validates :budget, :presence => true, :length => { :within => 1..10000000 }
end

上述为一种"sexy"方式;

当使用自定义验证时,"validates"方法的作用显现出来了:

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

在Rails中,所有的验证函数及常用的模型函数均被集成到了 ActiveModel中,因此可以使用validations and Validator类来代替ActiveRecord,例如:

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

原文地址: http://thelucid.com/2010/01/08/sexy-validation-in-edge-rails-rails-3/