Order.cs

using System.Collections.Generic;

namespace Models
{
  public class Order
  {
    public int order_id { get; set; }
    public string customer_email { get; set; }
    public IEnumerable<OrderDetail> details { get; set; }
  }

  public class OrderDetail
  {
    public string product_name { get; set; }
    public int quantity { get; set; }
  }

  public static class OrderUtil
  {
    public static Order GetTestOrder()
    {
      return new Order
      {
        order_id = 1,
        customer_email = "jason@gms.ndhu.edu.tw",
        details = new List<OrderDetail> {
          new OrderDetail{ product_name = "basketball", quantity = 100 },
          new OrderDetail { product_name = "soccer", quantity = 50 }
        }
      };
    }
  }
}