Question

我无法为linq sql选择器的连接部分创建可重用的选择器。它现在如何运作：

var result = (from player in context.Players
select new
{
    FullName = (string.IsNullOrEmpty(player.FirstName) ? string.Empty : player.FirstName + " ") + player.LastName
    FirstName = player.FirstName,
    LastName = player.LastName,
    Street = player.Street,
}).FirstOrDefault();

我的需要:(我想在多个其他linq sql查询中重用DynamicFullNameSelector()）

var result = (from player in context.Players
select new
{
    FullName = DynamicFullNameSelector(),
    FirstName = player.FirstName,
}).FirstOrDefault();

我尝试了LINQ Dynamic Expressions芽的部分我不知道如何存档。

我也尝试过:(使用Combine功能）

Expression<Func<Player, string>> firstName = p => p.FirstName;
Expression<Func<Player, string>> lastName = p => p.LastName;
Expression<Func<Player, string>> fullnameJoin = DynamicQueryable.Combine(firstName, lastName, (a, b) => a + ", , " + b);

var result = (from player in context.Players
select new
{
    FullName = fullnameJoin,
    FirstName = player.FirstName,
}).FirstOrDefault();

Bud然后我得到如下例外：'LINQ to Entities中不支持LINQ表达式节点类型'Lambda'。'

有什么想法吗？

可重用实体linq sql选择部分

0 个答案: