Question

我想使用Linq选择一个对象，其中一个元素是一个数字，我想在运行时将其格式化为一个字符串。我想创建一个特定的描述文本，包括其他列的一些数据。如果你看一下select-sentence，我试着将字符串格式化为带有两位小数的货币，这是行不通的。我该如何正确地做到这一点？

var stuff = from obj in _dbc.Stuff
 where
     SqlMethods.Like(obj.SEGMENT2, "0023") &&
     SqlMethods.Like(obj.SEGMENT4, "1243") 
 group obj by new
     {
         obj.SEGMENT1
     }
 into g
 select new StuffObject
 {
     Item = g.Key.SEGMENT1,
     Description = 
         string.Format("{0:C2}", g.Sum(p => p.VALUE == null ? 0 : p.VALUE.Value))  //<-- This is not working for me
         + "<br/>" + g.Min(p => p.DESCRIPTION),
     DeCode = g.Min(p => p.SEGMENT2),
     CeCode = g.Min(p => p.SEGMENT4),
     QTY = g.Sum(p => p.QUANTITY == null ? 0 : (int)p.QUANTITY),
     Cost = g.Sum(p => p.VALUE == null ? 0 : (double)p.VALUE)
 };

顺便说一下，我收到的错误代码是： System.InvalidOperationException: Could not translate expression .... abbreviated ...into SQL and could not treat it as a local expression.

我的StuffObject类现在（我还没试过@Grundy回答）：

public class StuffObject
{
    public string Item { get; set; }
    public string Description { get; set; }
    public string DeCode { get; set;}
    public string CeCode { get; set; }
    public int QTY{ get; set; }
    public double Cost { get; set; }
}

Answer 1

LINQ无法将string.Format转换为SQL，因此您需要摆脱它。您可以更改StuffObject之类的

public class StuffObject{
    ....
    private decimal sumValue;
    private decimal description;
    public string Description {
        get{
            return string.Format("{0:C2}<br/>{1:C2}", sumvalue,description);
        }
    }
    ....
}

然后像这样更改LINQ查询

....
select new StuffObject
{
    Item = g.Key.SEGMENT1,
    description =g.Min(p => p.DESCRIPTION),
    sumValue =g.Sum(p => p.VALUE == null ? 0 : p.VALUE.Value),
    DeCode = g.Min(p => p.SEGMENT2),
    CeCode = g.Min(p => p.SEGMENT4),
    QTY = g.Sum(p => p.QUANTITY == null ? 0 : (int)p.QUANTITY),
    Cost = g.Sum(p => p.VALUE == null ? 0 : (double)p.VALUE)
};

使用Linq将格式化字符串选择为对象

1 个答案: