Asp.net VB.NET GridView忽略页脚合计中的空值

VB.net

HTML:

我希望能够对这些值求和：

Month   Value
Jan     NULL
Feb     NULL
Mar     15.00
Apr     10.00

但是，我发现错误

无法将对象从DBNull强制转换为其他类型。

有没有办法在页脚中添加总计而忽略空值？

试试这个

   Month   Value
    Jan     NULL
    Feb     NULL
    Mar     15.00
    Apr     10.00
   Total    25.00

编辑

首先，应该始终使用而不是Convert.ToDecimal（）

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感谢您的帮助，但我发现错误

输入字符串的格式不正确引用Dim rowtoal As Decimal=Convert.ToDecimal（DataBinder.Eval（例如Row.DataItem，“webShopTotal”）。ToString

使用Decimal.TryParse（value，out number）而不是Convert.ToDecimal

Month   Value
Jan     NULL
Feb     NULL
Mar     15.00
Apr     10.00

   Month   Value
    Jan     NULL
    Feb     NULL
    Mar     15.00
    Apr     10.00
   Total    25.00

Protected Sub monthlyReportsUK_RowDataBound(ByVal sender As Object, ByVal e As GridViewRowEventArgs)

If e.Row.RowType = DataControlRowType.DataRow Then    
 If DataBinder.Eval(e.Row.DataItem, "webShopTotal").ToString IsNot Nothing AndAlso DataBinder.Eval(e.Row.DataItem, "webShopTotal").ToString IsNot DbNull.Value Then
   Dim rowTotal As Decimal = Convert.ToDecimal(DataBinder.Eval(e.Row.DataItem, "webShopTotal").ToString)
   grdTotal = grdTotal + rowTotal
 End Id
End If

If e.Row.RowType = DataControlRowType.Footer Then
   Dim lbl As Label = DirectCast(e.Row.FindControl("lblwebsVal"), Label)
   lbl.Text = "£" + grdTotal.ToString("##,0.00")
End If

End Sub

Dim result  = 0
Dim rowTotal As Decimal = Decimal.TryParse(DataBinder.Eval(e.Row.DataItem, "webShopTotal").ToString), out result)