Question

我的课程定义如下：

public class SearchResult
{
    public Customer Customer { get; set; }
    public Receipt Receipt { get; set; }
    public IEnumerable<ReceiptDetail> ReceiptDetail { get; set; }
}

在我的Linq查询中，我想返回一个SearchResult记录，但在返回ReceiptDetail列表时遇到问题。如果我这样做：

 var list=(from cust in dbContext.Customers 
     join rec in dbContext.Receipts on cust.IdCustomer equals rec.IdCustomer
     join recdet in dbContext.ReceiptDetails on rec.IdReceipt equals recdet.IdReceipt
     select new SearchResult
     {
          Customer=cust,
          Receipt=rec,
          ReceiptDetail = (from  r1 in recdet select r1).ToList() // COMPILER ERROR HERE
     }).ToList();

我得到＆＃34;无法找到源类型ReceiptDetail的查询模式的实现＆＃39;选择＆＃39;找不到＆＃34;。

我做错了什么？

Answer 1

嗯，recdet来自这里：

join recdet in dbContext.ReceiptDetails on rec.IdReceipt equals recdet.IdReceipt

这意味着它是单收据明细。您之后尝试将其用作集合：

from  r1 in recdet select r1

我怀疑你真的想要一个小组加入：

join recdet in dbContext.ReceiptDetails on rec.IdReceipt equals recdet.IdReceipt
  into recdets
...
ReceiptDetail = (from  r1 in recdets select r1).ToList()

或更简单地用于后一部分：

ReceiptDetail = recdets.ToList()

在List中返回List时出现Linq错误

1 个答案: