Rails: Why is the “number_with_delimiter” method not recognized inside my model?

问题

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?

回答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.

回答2:

Instead of extending ActionView module. You can use methods from ActiveSupport instead

For example:

ActiveSupport::NumberHelper::number_to_currency(10000.1234,{precision: 2,unit: ''})

回答3:

You should use extend:

Usage: extend ActionView::Helpers::NumberHelper

It is good for me

回答4:

You might be missing the dependency... is the NumberHelper class accessible to your application?

Check the official Rails docs

来源：https://stackoverflow.com/questions/4467697/rails-why-is-the-number-with-delimiter-method-not-recognized-inside-my-model