如何获得配置在一个ActiveRecord验证的最大长度。 [英] How to get the maximum length configured in an ActiveRecord validation?

问题描述

给定一个模式：

class Person
  validates_lenght_of :name, :maximum => 50
end

我有一些看法code，显示倒计时并强制执行这个最大值。不过，我很难codeD数字50到该视图code。有没有办法从模型中提取这个数字？

I have some view code that shows a countdown and enforces this maximum. However I hard coded the number 50 into that view code. Is there a way to extract this number from the model?

是这样的：

Person.maximum_length_of_name

我尝试这样做：

I tried this:

Person.validators_on(:name)
 => [#<ActiveRecord::Validations::UniquenessValidator:0x000001067a9840 @attributes=[:name], @options={:case_sensitive=>true}, @klass=Trigger(id: integer, name: string, created_at: datetime, updated_at: datetime, user_id: integer, slug: string, last_update_by: integer)>, #<ActiveModel::Validations::PresenceValidator:0x000001067a6c30 @attributes=[:name], @options={}>, #<ActiveModel::Validations::LengthValidator:0x000001067a3f08 @attributes=[:name], @options={:tokenizer=>#<Proc:0x00000101343f08@/Users/sjors/.rvm/gems/ruby-1.9.2-p0/gems/activemodel-3.0.6/lib/active_model/validations/length.rb:9 (lambda)>, :maximum=>50}>]

中的信息就在那里，但我不知道如何提取它：

The information is in there, but I don't know how to extract it:

推荐答案

使用 validators_on 方法

irb(main):028:0> p Person.validators_on(:name)[0].options[:maximum]
50
=> 50

由于@Max威廉姆斯提到它只能on Rails的3

As @Max Williams mentioned it works only on Rails 3

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