rails3.0新的验证方法

rails3.0新的验证方法已经从Active Model中抽取出来,它接受一个属性和哈稀验证选项,不在像3.0以前针对每个属性使用一个验证方法,极大的简化了验证流程.

以前的方法虽然还在,但不推荐使用了,因为我们够懒.

下面我们先来看一个简单的示例:

class Person < ActiveRecord::Base
    validates :email, :presence => true
end

新的验证方法接收以下选项:

1. :acceptance => Boolean
2.  :confirmation => Boolean
3.  :exclusion => { :in => Ennumerable }
3.  :inclusion => { :in => Ennumerable }
4.  :format => { :with => Regexp }
5.  :length => { :minimum => Fixnum, maximum => Fixnum, }
6.  :numericality => Boolean
7.  :presence => Boolean
8.  :uniqueness => Boolean

更容易使用的验证选项,让验证更加轻松,我们以一个比较完整的验证用户名和电子邮件作为示例:

# app/models/person.rb
class User < ActiveRecord::Base
  validates :name,  :presence => true,
                    :length => {:minimum => 1, :maximum => 254}
                   
  validates :email, :presence => true, 
                    :length => {:minimum => 3, :maximum => 254},
                    :uniqueness => true,
                    :format => {:with => /^([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})$/i}
  
end

从示例中我们可以看到,模型的各个属性以及要进行何种验证,代码的可读性也得到了提升.

在了解rails 3.0验证方法的基本使用方法后,我们来看下一些更高级的应用.
当用户分为不同的等级,如游客,用户,客户等,它们共用preson模型,这时我们可以应用: validates_with

# app/models/person.rb
class User < ActiveRecord::Base
  validates_with HumanValidator
end

# app/models/person.rb
class Visitor < ActiveRecord::Base
  validates_with HumanValidator
end

# app/models/person.rb
class Customer < ActiveRecord::Base
  validates_with HumanValidator
end

然后在你项目的lib目录创建以下文件

class HumanValidator < ActiveModel::Validator

  def validate(record)
    record.errors[:base] << "This person is dead" unless check(human)
  end

  private

    def check(record)
      (record.age < 200) && (record.age > 0)
    end
end

启动控制台,运行以下代码,你就会看到效果:

$ ./script/console
Loading development environment (Rails 3.0.pre)
>> u = User.new
=> #<User id: nil, name: nil, email: nil, created_at: nil, updated_at: nil>
>> u.valid?
=> false
>> u.errors
=> #<OrderedHash {:base=>["This person is dead"]}>