LINQ到实体 - 把所有的字段到最后的结果

Question

让我们用这个查询为例（这个来自MSDN文档）：

ObjectSet<SalesOrderHeader> orders = context.SalesOrderHeaders; 
ObjectSet<SalesOrderDetail> details = context.SalesOrderDetails; 

var query = 
    from order in orders 
    join detail in details 
    on order.SalesOrderID equals detail.SalesOrderID 
    where order.OnlineOrderFlag == true 
    && order.OrderDate.Month == 8 
    select new 
    { 
     SalesOrderID = order.SalesOrderID, 
     SalesOrderDetailID = detail.SalesOrderDetailID, 
     OrderDate = order.OrderDate, 
     ProductID = detail.ProductID 
    }; 

如果我想要把所有出现在“命令”到田间地头最后的对象（即选择新的）除了来自细节的其他字段，我该怎么做呢？

Answer 1

var query = 
    from order in orders 
    join detail in details 
    on order.SalesOrderID equals detail.SalesOrderID 
    where order.OnlineOrderFlag == true 
    && order.OrderDate.Month == 8 
    select new 
    { 
     SalesOrderHeader = order; 
     SalesOrderDetail = detail; 
    }; 

Answer 2

你既可以恢复整个SalesOrderHeader对象在您的查询，或使用Include方法。

ObjectSet<SalesOrderHeader> orders = context.SalesOrderHeaders; 
ObjectSet<SalesOrderDetail> details = context.SalesOrderDetails; 

var query = 
    from order in orders 
    join detail in details 
    on order.SalesOrderID equals detail.SalesOrderID 
    where order.OnlineOrderFlag == true 
    && order.OrderDate.Month == 8 
    select new 
    { 
     SalesOrderID = order.SalesOrderID, 
     SalesOrderDetailID = detail.SalesOrderDetailID, 
     OrderDate = order.OrderDate, 
     ProductID = detail.ProductID, 
     Order = order 
    }; 

或者使用Include方法（假设你的SalesOrderHeader类有一个集合参考SalesOrderDetail类）：

ObjectSet<SalesOrderHeader> orders = context.SalesOrderHeaders; 
ObjectSet<SalesOrderDetail> details = context.SalesOrderDetails; 

var query = 
    (from order in orders 
    where order.OnlineOrderFlag == true 
    && order.OrderDate.Month == 8 
    select order).Include(x => x.Details); 

Answer 3

做这样的事情？

  var query = 
      from order in orders 
      join detail in details 
      on order.SalesOrderID equals detail.SalesOrderID 
      where order.OnlineOrderFlag == true 
      && order.OrderDate.Month == 8 
      select new 
      { 
       SalesOrderID = order.SalesOrderID, 
       SalesOrderDetailID = detail.SalesOrderDetailID, 
       OrderDate = order.OrderDate, 
       ProductID = detail.ProductID, 
       Order = order 
      };