在LINQ查询select语句中使用.ToString

Question

我有以下LINQ to实体查询(使用odp.net):

Dim query = from Elemento in X.VIEW
            where Elemento.code = "10"
            Select New With {Elemento.code, .Time = Elemento.Time.ToString("HH:mm")}
query.ToList()

代码会抛出该ToList()方法的异常:

LINQ to Entities does not recognize the method 'System.String ToString()'

我已经阅读了所有关于此的内容,但还没有找到一个简单的解决方法.

---

Lazyberezovsky有正确的答案,我之前无法让它工作,因为我这样做:

Dim query = (from Elemento in X.VIEW
            where Elemento.code = "10"
            Select New With {Elemento.code, Elemento.Time}).ToList
Dim query2 = from elemento in query
        Select New With {elemento.code, TIME = elemento.Time.ToString("HH:mm")}

Dim result = query2.ToList()

但这不起作用,显然你必须一步到位.

Answer 1

您可以将DateTime转换为字符串内存.只需ToList在转换时间之前拨打电话:

在C#中:

var query = from Elemento in X.VIEW
            where Elemento.code == "10"
            select new { Elemento.code, Elemento.Time };

var result = query.ToList() // now you are in-memory
                  .Select(x => new { x.code, Time = x.Time.ToString("HH:mm") });

在VB.Net中:

Dim query = From Elemento In X.VIEW
    Where Elemento.code = "10"
    Select New With {Elemento.code, Elemento.Time}

Dim result = query.ToList() _
    .Select(Function(x) New With {x.code, .Time = x.Time.ToString("HH:mm")})

BTW为什么要选择Elemento.code结果,如果你在哪里运算符过滤它(它总是等于"10").