Datagridview auto calculate columns.

[coolwater]

Need Help. I have a Datagridview that have the following columns.

1. ID
2. Products
3. Qty
4. UnitPrice
5. Total

The Products column is a combobox. The products combobox when selected will autofill the UnitPrice column. I have subroutine (GetOtherFeeAmount) that will get the UnitPrice from the database according to the item selected from the Products combobox.

The Problem: I get this error "Conversion from type 'DataRowView' to type 'Long' is not valid." The initial first row data entry is ok. I will always get this error everytime I go back and change a combobox selection.

This is where the error occurs highlighted in RED:

    Private Sub ComboBox_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs)

        Dim comboBox As ComboBox = CType(sender, ComboBox)

        If comboBox IsNot Nothing Then
            Dim cdecUnitPrice As Decimal
            cdecUnitPrice = GetOtherFeeAmount(GetDefaultSchoolYearOrSemester("School Year"), GetDefaultSchoolYearOrSemester("Semester Name"), comboBox.SelectedValue)
            dgvFees("UnitPrice", dgvFees.CurrentRow.Index).Value = cdecUnitPrice
            dgvFees("FeeAmount", dgvFees.CurrentRow.Index).Value = CInt(dgvFees("Qty", dgvFees.CurrentRow.Index).Value) * CDec(dgvFees("UnitPrice", dgvFees.CurrentRow.Index).Value)
        End If


    End Sub

My EditingControlShowing Code:

    Private Sub dgvFees_EditingControlShowing(sender As Object, e As System.Windows.Forms.DataGridViewEditingControlShowingEventArgs) Handles dgvFees.EditingControlShowing

        If TypeOf e.Control Is DataGridViewComboBoxEditingControl Then
            Dim te As DataGridViewComboBoxEditingControl = DirectCast(e.Control, DataGridViewComboBoxEditingControl)
            te.AutoCompleteMode = AutoCompleteMode.Suggest
            te.AutoCompleteSource = AutoCompleteSource.ListItems
            te.SelectedIndex = -1
            te.DropDownStyle = ComboBoxStyle.DropDownList
            te.FlatStyle = FlatStyle.Flat
        End If


        ''=====check if SLID combobox value is changed =======
        If dgvFees.CurrentCell.ColumnIndex = 1 And Not e.Control Is Nothing Then

            Dim comboBox As ComboBox
            comboBox = CType(e.Control, ComboBox)

            If (comboBox IsNot Nothing) Then
                RemoveHandler comboBox.SelectedIndexChanged, New EventHandler(AddressOf ComboBox_SelectedIndexChanged)

                'Add the event handler. 
                AddHandler comboBox.SelectedIndexChanged, New EventHandler(AddressOf ComboBox_SelectedIndexChanged)
            End If

        End If

        '=====code below is to control the user to input correct textbox entry
        If dgvFees.CurrentCell.ColumnIndex = 2 And Not e.Control Is Nothing Then

            Dim tb As TextBox = CType(e.Control, TextBox)
            '---add an event handler to the TextBox control---
            AddHandler tb.KeyPress, AddressOf TextBox_KeyPress

        End If

    End Sub

My CellEndEdit Code:

    Private Sub dgvFees_CellEndEdit(sender As Object, e As System.Windows.Forms.DataGridViewCellEventArgs) Handles dgvFees.CellEndEdit

        If dgvFees.CurrentCell.ColumnIndex = 2 Then

            Dim row As DataGridViewRow = dgvFees.Rows(e.RowIndex)

            Dim QtyValue As Decimal = row.Cells("Qty").Value
            Dim UnitPriceValue As Decimal = row.Cells("UnitPrice").Value
            Dim TotalAmountValue As Decimal = QtyValue * UnitPriceValue

            row.Cells("FeeAmount").Value = CDec(TotalAmountValue)

        ElseIf dgvFees.CurrentCell.ColumnIndex = 4 Then
            txtTotal.Text = GetTotal()
        End If

    End Sub

Any help will be highly appreciated.