实体框架中导航属性的属性总和

public class Customer
{
    public int CustomerId { get; set; }
    public string Name { get; set; }
    public virtual ICollection<Order> Orders { get; set; } // 导航属性
}

public class Order
{
    public int OrderId { get; set; }
    public DateTime OrderDate { get; set; }
    public int CustomerId { get; set; } // 外键
    public virtual Customer Customer { get; set; } // 导航属性
}

public class MyDbContext : DbContext
{
    public DbSet<Customer> Customers { get; set; }
    public DbSet<Order> Orders { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Customer>()
            .HasMany(c => c.Orders)
            .WithRequired(o => o.Customer)
            .HasForeignKey(o => o.CustomerId);
    }
}

using (var context = new MyDbContext())
{
    var customerWithOrders = context.Customers
        .Where(c => c.CustomerId == 1)
        .Include(c => c.Orders)
        .FirstOrDefault();

    if (customerWithDetails != null)
    {
        Console.WriteLine($"Customer: {customerWithDetails.Name}");
        foreach (var order in customerWithDetails.Orders)
        {
            Console.WriteLine($"Order Date: {order.OrderDate}");
        }
    }
}