Rails: Add error message through model to the controller

Question

So far I understood that you only can raise error messages in the controller. The Sale model is a child of the Order model. So I did this:

class SalesController < ApplicationController
 def create
  ...
  if @sale.errors.any?
   flash[:error] = "#{@order.sale.errors.full_messages.to_sentence}"
  end
 end

class Sale < ActiveRecord::Base
before_save :discount

def discount=(discount)
 if discount.present?
  if current_user.maxdiscount >= discount.to_d
    discount = discount.gsub(",", ".")
    self[:discount] = discount
  else
    self.errors.add(:discount, "The discount is too high. The product was added without it.")
  end
 end
end

But that does not work. The main goal is to raise an error message whenever a user tries to submit a value that is bigger than the current_user.maxdiscount .

Any Ideas? Thanks in advance!

Answer 1

Yes, you can record error messages at Model level.

But as you do it in callback, you have to stop the transaction by returning false or raise an error manually.

class Sale < ActiveRecord::Base
   before_save :discount

   def discount=(discount)
     if discount.present?
      if current_user.maxdiscount >= discount.to_d
        discount = discount.gsub(",", ".")
        self[:discount] = discount
      else
        self.errors.add(:discount, "The discount is too high. The product was added without it.")
        return false
      end
   end
end