I have class bill like below
class Bill < ActiveRecord::Base
#total = field in database
has_many :items
after_save :calculate_total
def calculate_total total = self.items.map{|item| item.price}.sum end
end
From the code above, the total will be auto calculated from on the price on each items in this bill. However, user can try to assign the value of this bill but when save the value with be replace with after_save calculate_total.
The question is
Do we have a way to prevent user to directly assign the total value but allow the calculate_total to assign the value?