Rails：为什么是“number_with_delimiter”？在我的模型中无法识别的方法？ [英] Rails: Why is the "number_with_delimiter" method not recognized inside my model?

问题描述

我有一个简单的验证：

class Product < ActiveRecord::Base
  # include ActionView::Helpers::NumberHelper
  ...
  validates_numericality_of :price, :less_than => 1000000, 
                            :message => "must be less than #{number_with_delimiter(1000000)}"                       
  ...
end

在此代码中，我收到以下错误：

On this code, I have received the following error:

undefined method `number_with_delimiter' for #<Class:0x2665a58>

我试图添加：

include ActionView::Helpers::NumberHelper

但它没有帮助。

我缺少什么？

推荐答案

真正的问题这里是你将这个模块包含在类中，而不是用它扩展类。

The true problem here is that you're including this module into the class, rather than extended the class with it.

包含的差异将使方法在实例上可用，扩展的位置将使它们成为你尝试使用它们的地方：在课堂上。

The differences is an include will make the methods available on the instance, where as the extend will make them where you're trying to use them: on the class.

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