.all?这是一个ruby方法，他的返回结果只有两个，true或者false，判断的是数组中每一个元素都是true的就返回true，只要有一个不是true就返回false，如[nil,22].all?返回的就是false。还有就是判断数组遍历运算过程中，每一个结果是不是true，如[1,2,3].all?{|w| w >1}这个的结果就是false。

你的例子中，作为判断对象的是一个空数组，不执行后面的代码，也没有一个元素是false的，所以返回的是true，这是我的见解

@cache ||= {} 如果 @cache 已有资料, 那就不做动作

其相当於 @cache || @cache = {}

也就是

if ( @cache ) { }

else { @cache = {} }

而 @cache = {} 就是, 无论@cache 有无资料,

都将其清空, 回到初始化的状态

Ruby on Rails 的检验方法(Validation Helpers)大全

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 must specify 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:

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:“must be 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 match confirmation.”

:on :save, :create, or :update

实例:

对密码表:

#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_nil boolean 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|

if value =~ /groucho|harpo|chico/i

model.errors.add(attr,"You can'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

:is integer

:minimum integer

:maximum integer

: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_long text 当使用了 :maximum后的 :message

:too_short text ( :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 been taken.”

: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 =>

/(^$)|(^(http|https)://[a-z0-9] ([-.]{1}[a-z0-9] )*.[a-z]{2,5}(([0-9]{1,5})?/.*)?$)/

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