Question

在我的父子方案中，我需要获得所有客户的自定义列表及其订单总数和订单项。

客户可以拥有多个订单，订单可以包含许多OrderItem。我需要编写一个查询，它返回实体对象的集合，该对象具有该Customer对象的Customer Entity和Total Orders以及Total OrderItem，例如

var result = from c in  ctx.Customers
         from o in  ctx.Orders
         from d in  ctx.OrderItems
         select new List<CustomerVM()
         {
            customer = c,
            totalOrders = o.Count,
            totalOrderItems = XXXX  
         }  
public class CustomerVM {
 public Customer customer {get; set;}
 public int totalOrders {get; set;}
public int totalOrderItems {get; set;}
}

我该怎么做？

Answer 1

您需要使用SelectMany：

var result = (from c in ctx.Customers
              select new CustomerVM
              {
                  customer = c,
                  totalOrders = c.Orders.Count(),
                  totalOrderItems = c.Orders.SelectMany(o => o.OrderItems).Count()
              }).ToList();

Linq查询获取Child的子记录

1 个答案: