Question

在执行NetValueValidation（）时，我得到以下括号内的错误（操作符' - '未定义类型'Double'并键入'DBNull'。）。但是在执行DiscPerValidation（）

后，它在“discper”列中工作

Private Sub grdPurchase_CellEndEdit(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles grdPurchase.CellEndEdit
    CellEdited = True
    CurrentColumn = e.ColumnIndex
    CurrentRow = e.RowIndex
    If Me.grdPurchase.Columns(Me.grdPurchase.CurrentCell.ColumnIndex).Name = "itemcode" Then
        If Not Me.grdPurchase.Rows(e.RowIndex).Cells("itemcode").Value Is DBNull.Value Then
            SeekItemDetails()
        End If
    Else
        If Me.grdPurchase.Columns(Me.grdPurchase.CurrentCell.ColumnIndex).Name = "packingratio" Then
            PackingRatioValidation()
        ElseIf Me.grdPurchase.Columns(Me.grdPurchase.CurrentCell.ColumnIndex).Name = "price" Then
            PriceValidation()
            NetValueValidation()
        ElseIf Me.grdPurchase.Columns(Me.grdPurchase.CurrentCell.ColumnIndex).Name = "grossamt" Then
            GrossAmtValidation()
            'NetValueValidation()
        ElseIf Me.grdPurchase.Columns(Me.grdPurchase.CurrentCell.ColumnIndex).Name = "kgs" Then
            KGSValid()
            'NetValueValidation()
        ElseIf Me.grdPurchase.Columns(Me.grdPurchase.CurrentCell.ColumnIndex).Name = "discper" Then
            DiscPerValidation()
            'NetValueValidation()
        End If
        SendKeys.Send("{UP}" + "{TAB}")
    End If
End Sub

Private Sub PackingRatioValidation()
    If Not Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("packingratio").Value Is DBNull.Value And _
            Not Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("packingratio_temp").Value Is DBNull.Value And _
            Not Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("itemcode").Value Is DBNull.Value Then
        Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("qty").Value = _
            Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("packingratio").Value * _
            Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("packingratio_temp").Value
    End If
End Sub

Private Sub PriceValidation()
    If Not Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("itemcode").Value Is DBNull.Value And _
            Not Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("qty").Value Is DBNull.Value And _
            Not Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("price").Value Is DBNull.Value Then
        Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("grossamt").Value = Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("price").Value * _
            Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("qty").Value
    End If
End Sub

Private Sub GrossAmtValidation()
    If Not Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("itemcode").Value Is DBNull.Value And _
            Not Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("qty").Value Is DBNull.Value And _
            Not Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("grossamt").Value Is DBNull.Value Then
        Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("price").Value = Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("grossamt").Value / _
            Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("qty").Value
    End If
End Sub

Private Sub KGSValid()
    If Not Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("itemcode").Value Is DBNull.Value And _
            Not Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("qty").Value Is DBNull.Value And _
            Not Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("price").Value Is DBNull.Value And _
            Not Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("grossamt").Value Is DBNull.Value Then
        Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("kgrate").Value = Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("grossamt").Value / _
            Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("kgs").Value
    End If
End Sub

Private Sub DiscPerValidation()
    If Not Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("itemcode").Value Is DBNull.Value And _
            Not Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("grossamt").Value Is DBNull.Value And _
            Not Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("discper").Value Is DBNull.Value Then
        Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("discamt").Value = _
            (Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("grossamt").Value / 100) * _
            Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("discper").Value
    End If
End Sub

Private Sub NetValueValidation()
    If Not Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("itemcode").Value Is DBNull.Value And _
    Not Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("grossamt").Value Is DBNull.Value Then
        Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("netvalue").Value = _
        Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("grossamt").Value - _
        Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("discamt").Value
    End If
End Sub

Answer 1

该消息表示在此代码中：

Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("grossamt").Value - _    
Me.grdPurchase.Rows(Me.grdPurchase.CurrentCell.RowIndex).Cells("discamt").Value

2个单元格中的一个是DBNull。根据消息，它是一个参与减法的单元格，这就是这些2.奇怪的是，你在DBNull的单元格之后测试单元格，而不是在这里。

不是没有，但是你有很多不必要的代码，这使得很难看到这种类型的东西。例如，CellEndEdit中的大块If可以简化为：

Dim name As String = dgv2.Rows(e.ColumnIndex).Cells(e.ColumnIndex).Value.ToString
Select Case name
    Case "price"
        PriceValidation(e.RowIndex)
        NetValueValidation(...)
    Case "grossamt"
        GrossAmtValidation(...)
End Select

我不确定你为什么不使用可用的事件args。那么PriceValidation所需要的就是这样的东西（将行传递给EventArgs）：

Private Sub PriceValidation(r As Int32) 
    ' note: this is DOING pricing, not validation
    Dim quan = SafeConvert(dgv.Rows(r).Cells("qty").Value)
    Dim price = SafeConvert(dgv.Rows(r).Cells("price").Value)

    dgv.Rows(r).Cells("grossamt").Value = (quan * price)
End Sub

我怀疑Option Strict没有开启 - 但它应该是：

grdPurchase.Rows(...).Cells("qty").Value = _
grdPurchase.Rows(...).Cells("packingratio").Value * _
grdPurchase.Rows(...).Cells("packingratio_temp").Value

单元格值返回对象，而不是数字，因此代码尝试将2个对象相乘。您可以使用一个简单的过程来测试 value 单元格上的DBNull（以上在PriceValidation中使用）：

' helper function to convert a DBNull
Private Function SafeConvert(v As Object) As Double
    If System.DBNull.Value.Equals(v) Then
        Return 0
    Else
        Dim d As Double = 0
        If Double.TryParse(v.ToString, d) Then

        End If
        Return d
    End If
End Function

它适用于具有数量或价格但不包含物料代码（文本）的单元格。每当你发现自己一遍又一遍地（或以上）输入相同的代码时，请停下来寻找更好的方法。

运算符' - '未定义为类型'Double'并键入'DBNull'。 [vb.net datagridview]

1 个答案: