无法创建仅匿名类型的类型为匿名类型的常量值 [英] unable to create a constant value of type anonymous type only primitive types

问题描述

使用Entity Framework版本= 6.0.0.0来获取通用ID和订单ID，如下所示.

Using Entity Framework Version=6.0.0.0 to get to get common id and orderid as shown below.

var dt1 = from p in dt.AsEnumerable()
          select new
          {
              Id = p.Field<int>("Id"),
              OrderId = p.Field<int>("OrderId")
          };

var dt2 = (from order in db.Orders
           select new
           {
               order.Id,
               order.OrderId
           }).ToList();
var intersect = dt1.Intersect(dt2);

基于相交值列表.我需要从订单表"中选择所有值.

Based on the list of values in intersect. I need to select all the values from Orders Table.

试图使用代码获取错误无法创建仅匿名类型的常量类型的常量值"

Trying to used code getting error "unable to create a constant value of type anonymous type only primitive types"

var result= (from a in sync.Orders
              where intersect.Any(b => a.Id == b.Id && a.OrderId == b.OrderId)
              select a).ToList();

推荐答案

您正尝试将EF查询与内存中的数据集联接"，该操作不起作用，因为无法嵌入列表和在SQL中查找.一种选择是使用AsEnumerable将整个表拉入内存:

You are trying to "join" an EF query with an in-memory data set, which does not work because there's not a way to embed the list and the lookup in SQL. One option is to pull the entire table into memory with AsEnumerable:

var result= (from a in sync.Orders.AsEnumberable
              where intersect.Any(b => a.Id == b.Id && a.OrderId == b.OrderId)
              select a).ToList();

另一种选择是将Id和OrderId连接为一个值并使用Contains，因为可以将其转换为SQL中的IN子句:

Another option is to concatenate the Id and OrderId into one value and use Contains since that can be translated to an IN clause in SQL:

var lookup = intersect.Select(i => i.Id + "-" + i.OrderId).ToList();

var result= (from a in sync.Orders
              where lookup.Contains(a.Id + "-" + a.OrderId)
              select a).ToList();

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