如何在Rails的数据库中保存参数？

Question

My rails app has an Operator model and a Booking model and they are related by the following relation:

class Booking < ActiveRecord::Base
    belongs_to :operator
end

My app further allows users to find cabs at a particular day and time, from a pickup location to a drop location, and book the cab, after checking the fares, thus creating an entry in the Booking model in the database. When creating a new booking, the user is presented with a typical form ('user_form') where they enter their name and other details. These details are stored in the bookings table in the database in appropriate columns.

I want my app to be able to store three more parameters in the bookings table, without these parameters being filled up through the user_form. These parameters are: pickup location, drop location and the fare.

The pickup and the drop locations are filled up by the user while searching the cabs, whereas the fare parameter is displayed to the user after making some internal calculations based on business logic. I can't pass these parameters as params , as these are sensitive parameters, and if tampered, they can have negative consequences for the business.

My bookings table has appropriate columns to store these parameters. Also, my bookings_controller allows these parameters to be saved as strong parameters. How do I save these three parameters in my bookings table while creating a new booking for an operator? Can furnish more details if required.

Answer 1

I would use attr_accessor to store the relevant params from the form, and then have a before_validation method to look at these and calculate the fare. This can do the calculation for the fare and write it into the database. eg

#in booking
attr_accessor :foo


before_validation :calculate_fare_if_foo


def calculate_fare_if_foo
  unless self.foo.blank?
    #do some calculation based on foo and the other attributes, to set self.fare
  end
end