Question

I have a simple validation:

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

On this code, I have received the following error:

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

I tried to add:

include ActionView::Helpers::NumberHelper

but it didn’t help.

What am I missing?

Answer 1

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

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.

For instance method use

include ActionView::Helpers::NumberHelper

For class method use

extend ActionView::Helpers::NumberHelper