I'm creating a ticket booking app as my sample project using Ruby on Rails 4.1. Three are three models - Events, Tickets and Bookings. Events have many tickets and bookings. Tickets have many bookings and they belong to events. Bookings belongs to events and tickets.

Tickets model has the price field and bookings model has the order_quantity field. Right now, I use a model method total_amount in bookings.rb to display the total price ie. (price * order_quantity) in the bookings show page (@booking.total_amount).

Now, in the bookings index page, I use a block to list all the details Buyer name, ticket type, order quantity etc. Here, I'd like to show the total amount as well. What's the best way to do it? Do I need to create a total_price column in the bookings table and save the amount in the create action?

<% @event.bookings.each do |booking| %>
              <td><%= booking.buyer_name %></td>
              <td><%= booking.email %></td>
              <td><%= booking.ticket_id %></td>
              <td><%= booking.order_quantity %></td>
<% end%>