Ruby on Rails 的模型 validates 驗證

validate(), 這個方法在每次保存數據時都會被調用.
如:
def validate
 if name.blank? && email.blank?
  errors.add_to_base("You must specify a name or an email address")
 end
end
同時也能夠自定義 validate_on_create(), validate_on_update()方法.
 valid?()方法能夠隨時調用,用來測試數據是否能經過校驗
返回的錯誤信息可用 error_messages_for(model)方法顯示.
如:<%= error_messages_for 'article' %>

校驗大全:
validates_acceptance_of
 指定checkbox應該選中. (如:(*)我贊成條款)
 用法:validates_acceptance_of attr... [ options... ]
 參數:message text  默認:「must be accepted.」
   :on :save, :create, or :update
 實例:
 class Order < ActiveRecord::Base
  validates_acceptance_of :terms,
              :message => "Please accept the terms to proceed"
 end

validates_associated
 查驗指定的object.
 用法:validates_associated name... [ options... ]
 參數:message text 默認: is 「is invalid.」
   :on :save, :create, or :update
 實例:
 class Order < ActiveRecord::Base
  has_many :line_items
  belongs_to :user
  validates_associated :line_items,
            :message => "are messed up"
  validates_associated :user
 end

validates_confirmation_of
 數據重校
 用法:validates_confirmation_of attr... [ options... ]
 參數:message text 默認 「doesn’t match confirmation.」
   :on :save, :create, or :update
 實例:
 對密碼錶:
 <%= password_field "user", "password" %>

 <%= password_field "user", "password_confirmation" %>

 #第二表名爲xxxx_confirmation
 class User < ActiveRecord::Base
  validates_confirmation_of :password
 end

validates_each
 使用block檢驗一個或一個以上參數.
 用法:validates_each attr... [ options... ] { |model, attr, value| ... }
 參數:allow_nil boolean 設爲true時跳過nil對象.
   :on :save, :create, or :update
 實例:
 class User < ActiveRecord::Base
  validates_each :name, :email do |model, attr, value|
   if value =~ /groucho|harpo|chico/i
    model.errors.add(attr,"You can't be serious, #{value}")
   end
  end
 end

validates_exclusion_of
 肯定被檢對象不包括指定數據
 用法:validates_exclusion_of attr..., :in => enum [ options... ]
 #enum指一切可用include?()判斷的範圍.
 參數:allow_nil 設爲true將直接跳過nil對象.
   :in (or :within) enumerable 
   :message text 默認爲: 「is not included in the list.」
   :on :save, :create, or :update
 實例:
 class User < ActiveRecord::Base
  validates_exclusion_of :genre,
            :in => %w{ polka twostep foxtrot },
            :message =>"no wild music allowed"
  validates_exclusion_of :age,
             :in => 13..19,
             :message =>"cannot be a teenager"
 end

validates_inclusion_of
 確認對象包括在指定範圍
 用法:validates_inclusion_of attr..., :in => enum [ options... ]
 參數:allow_nil 設爲true直接跳過nil對象
   :in (or :within) enumerable An enumerable object.
   :message text 默認:「is not included in the list.」
   :on :save, :create, or :update
 實例:
 class User < ActiveRecord::Base
  validates_inclusion_of :gender,
            :in => %w{ male female },
            :message =>"should be 'male' or 'female'"
  validates_inclusion_of :age,
            :in => 0..130,
            :message =>"should be between 0 and 130"
 end

validates_format_of
 用正則檢驗對象
 用法:validates_format_of attr..., :with => regexp [ options... ]
 參數:message text 默認爲: 「is invalid.」
   :on :save, :create, or :update
   :with 正則表達式
 實例:
 class User < ActiveRecord::Base
  validates_format_of :length, :with => /^/d+(in|cm)/
 end

validates_length_of
 檢查對象長度
 用法:validates_length_of attr..., [ options... ]
 參數:in (or :within) range 
   :is integer 
   :minimum integer 
   :maximum integer 
   :message text 默認文字會根據參數變更,可以使用%d 取代肯定的最大,最小或指定數據.
   :on :save, :create, or :update
   :too_long text 當使用了 :maximum後的 :message 
   :too_short text ( :minimum )
   :wrong_length ( :is)
 實例:
 class User < ActiveRecord::Base
  validates_length_of :name, :maximum => 50
  validates_length_of :password, :in => 6..20
  validates_length_of :address, :minimum => 10,
                :message =>"seems too short"
 end

validates_numericality_of
 檢驗對象是否爲數值
 用法:validates_numericality_of attr... [ options... ]
 參數:message text 默認 「is not a number.」
   :on :save, :create, or :update
   :only_integer 
 實例:
 class User < ActiveRecord::Base
  validates_numericality_of :height_in_meters
  validates_numericality_of :age, :only_integer => true
 end

validates_presence_of
 檢驗對象是否爲空
 用法:validates_presence_of attr... [ options... ]
 參數:message text 默認:「can’t be empty.」
   :on :save, :create, or :update
 實例:
 class User < ActiveRecord::Base
  validates_presence_of :name, :address
 end

validates_uniqueness_of
 檢驗對象是否不重複
 用法:validates_uniqueness_of attr... [ options... ]
 參數:message text 默認: 「has already been taken.」
   :on :save, :create, or :update
   :scope attr 指定範圍
 實例:
 class User < ActiveRecord::Base
  validates_uniqueness_of :name
 end

 class User < ActiveRecord::Base
  validates_uniqueness_of :name, :scope =>"group_id"
 end
 #指定在同一group_id的條件下不重複.

經常使用正則:

E-Mail地址格式:
validates_format_of     :email,
                        :with       => /^([^@/s]+)@((?:[-a-z0-9]+/.)+[a-z]{2,})$/i,
                        :message    => 'email must be valid'

網址格式:validates_uri_existence_of :url, :with =>        /(^$)|(^(http|https)://[a-z0-9] ([-.]{1}[a-z0-9] )*.[a-z]{2,5}(([0-9]{1,5})?/.*)?$)/ix