实体框架从导航属性对象中选择几个字段

var result = context.Orders
    .Select(o => new { o.OrderId, o.OrderDate, o.CustomerName })
    .ToList();

public class OrderDTO
{
    public int OrderId { get; set; }
    public DateTime OrderDate { get; set; }
    public string CustomerName { get; set; }
}

var result = context.Orders
    .Select(o => new OrderDTO { OrderId = o.OrderId, OrderDate = o.OrderDate, CustomerName = o.CustomerName })
    .ToList();

var result = context.Orders
    .Include(o => o.Customer)
    .Select(o => new { o.OrderId, o.OrderDate, o.Customer.CustomerName })
    .ToList();