using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using EntityFrameworkCore.Projections; namespace ReadmeSample.Entities { public class Order { public int Id { get; set; } public int UserId { get; set; } public DateTime CreatedDate { get; set; } public decimal TaxRate { get; set; } public User User { get; set; } public ICollection Items { get; set; } [Projectable] public decimal Subtotal => Items.Sum(item => item.Product.ListPrice * item.Quantity); [Projectable] public decimal Tax => Subtotal * TaxRate; [Projectable] public decimal GrandTotal => Subtotal + Tax; } }