如何在Linq中处理除零

Question

在下面的linq查询中，我有一个除零异常，我似乎无法编码。当fldDevider的Sum返回0时发生。

Dim lstToReturn As List(Of MonthData)
lstToReturn = (
 From myRow In dtSpotData.AsEnumerable()
 Group myRow By myRow.Field(Of DateTime)(fldstartdate).Month Into Group
 Select New MonthData() With {
 .Month = Month,
 .ValuePerMonth =
 (
  Group.Sum(Function(dr) dr.Field(Of [Decimal])(fldSomeGeneralValue)) /
  (
   Group.Sum(Function(dr) CDec(dr.Field(Of String)(fldDevider)))
  )
 )
 }
).ToList()

如何确保ValuePerMonth字段为0时，Group.Sum(Function(dr) CDec(dr。Field(Of String)(fldDevider))函数返回0。或者，如果Sum fldDevider实际上是0，我如何返回1 ?

也欢迎提供一些关于如何更好地从字符串转换为十进制的技巧。

Answer 1

我习惯c#语法，但我会使用'let'来捕获除法数的值，并且仅在它大于零时使用它，否则使用1。

Dim lstToReturn As List(Of MonthData)
lstToReturn = (
 From myRow In dtSpotData.AsEnumerable()
 Group myRow By myRow.Field(Of DateTime)(fldstartdate).Month Into Group
 Let div = Group.Sum(Function(dr) CDec(dr.Field(Of String)(fldDevider)))
 Select New MonthData() With {
 .Month = Month,
 .ValuePerMonth =
 (
  Group.Sum(Function(dr) dr.Field(Of [Decimal])(fldSomeGeneralValue)) / If(div > 0, div, 1)
 )
 }
).ToList()