使用LINQ和Entity Framework添加前导零

Question

我尝试通过Linq在我的ASP MVC应用程序中添加前导零:

int length = 4;
IEnumerable<object> query = [...]
select new
    {
        Seq = a.Seq.ToString("D" + length),
    }).OrderBy(a =>a.Seq).ToList();

..但我收到以下错误:

Additional information: LINQ to Entities does not recognize the method 'System.String ToString(System.String)' method, and this method cannot be translated into a store expression.

这样做的正确方法是什么？

Answer 1

我认为String.PadLeft是支持的(至少在Linq-To-Sql中它可以工作):

Seq = a.Seq.PadLeft(length, '0')}

如果这不起作用(我无法测试)你可以使用SqlFunctions.Replicate:

Seq = SqlFunctions.Replicate("0", length - a.Seq.ToString().Length) + a.Seq

(长度计算需要修改,希望你明白了)