validates

可以自定义validate(), 这个方法在每次保存数据时都会被调用.
如:
def validate
if name.blank? && email.blank?
    errors.add_to_base("You mustspecify a name or an email address")
end
end
同时也可以自定义 validate_on_create(),validate_on_update()方法.
valid?()方法可以随时调用,用来测试数据是否能通过校验
返回的错误信息可用 error_messages_for(model)方法显示.
如:<%= error_messages_for 'article' %>

校验大全:
validates_acceptance_of
指定checkbox应该选中. (如:(*)我同意条款)
用法:validates_acceptance_of attr... [ options...]
参数:message text    默认:“mustbe accepted.”
     :on :save,:create, or :update
实例:
class Order < ActiveRecord::Base
    validates_acceptance_of:terms,
                :message=> "Please accept the terms to proceed"
end
validates_associated
查验指定的object.
用法:validates_associated name... [ options...]
参数:message text 默认: is “is invalid.”
     :on :save,:create, or :update
实例:
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
数据重校
用法:validates_confirmation_of attr... [options... ]
参数:message text 默认 “doesn’t matchconfirmation.”
     :on :save,:create, or :update
实例:
对密码表:
<%= password_field "user", "password"%><br />
<%= password_field "user","password_confirmation" %><br />
#第二表名为xxxx_confirmation
class User < ActiveRecord::Base
    validates_confirmation_of:password
end
validates_each
使用block检验一个或一个以上参数.
用法:validates_each attr... [ options... ] {|model, attr, value| ... }
参数:allow_nilboolean 设为true时跳过nil对象.
     :on :save,:create, or :update
实例:
class User < ActiveRecord::Base
    validates_each :name, :email do|model, attr, value|
     ifvalue =~ /groucho|harpo|chico/i
      model.errors.add(attr,"Youcan't be serious, #{value}")
     end
    end
end
validates_exclusion_of
确定被检对象不包括指定数据
用法:validates_exclusion_of attr..., :in =>enum [ options... ]
#enum指一切可用include?()判断的范围.
参数:allow_nil 设为true将直接跳过nil对象.
     :in (or:within) enumerable
     :message text默认为: “is not included in the list.”
     :on :save,:create, or :update
实例:
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
确认对象包括在指定范围
用法:validates_inclusion_of attr..., :in =>enum [ options... ]
参数:allow_nil 设为true直接跳过nil对象
     :in (or:within) enumerable An enumerable object.
     :message text默认:“is not included in the list.”
     :on :save,:create, or :update
实例:
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
用正则检验对象
用法:validates_format_of attr..., :with =>regexp [ options... ]
参数:message text 默认为: “is invalid.”
     :on :save,:create, or :update
     :with正则表达式
实例:
class User < ActiveRecord::Base
    validates_format_of :length,:with => /^\d+(in|cm)/
end
validates_length_of
检查对象长度
用法:validates_length_of attr..., [ options...]
参数:in (or :within) range
     :isinteger
     :minimuminteger
     :maximuminteger
     :message text默认文字会根据参数变动,可使用%d取代确定的最大,最小或指定数据.
     :on :save,:create, or :update
     :too_longtext 当使用了 :maximum后的 :message
     :too_shorttext ( :minimum )
     :wrong_length( :is)
实例:
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
检验对象是否为数值
用法:validates_numericality_of attr... [options... ]
参数:message text 默认 “is not a number.”
     :on :save,:create, or :update
     :only_integer
实例:
class User < ActiveRecord::Base
    validates_numericality_of:height_in_meters
    validates_numericality_of :age,:only_integer => true
end
validates_presence_of
检验对象是否为空
用法:validates_presence_of attr... [ options...]
参数:message text 默认:“can’t be empty.”
     :on :save,:create, or :update
实例:
class User < ActiveRecord::Base
    validates_presence_of :name,:address
end
validates_uniqueness_of
检验对象是否不重复
用法:validates_uniqueness_of attr... [ options...]
参数:message text 默认: “has already beentaken.”
     :on :save,:create, or :update
     :scope attr指定范围
实例:
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的条件下不重复.

常用正则:

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

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