[RESOLVED] [2005] DataGridView Cell Check for number

[MechEng]

Greeting All,

I have a DataGridView question:

I have a DataGridView that has only one column that the user will use to input data and I want all data entered into this cell to be a number. I am using the following code to check the data entered into the cell during the CellLeave event. The event is firing and I am able to test the cell, but how can I stop the update process once I have tested the cell for a number. Currently, I have the DefaultDataError eventhandler set to do nothing, but it seams there would be a cleaner way.

Thanks for your help.

    Private Sub DataGridView3_CellLeave(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DataGridView3.CellLeave
        'Check for number values only in the Weight cell.
        Dim int_test As Short

        If Me.DataGridView3.CurrentCell.ColumnIndex = 2 Then

            Try
                int_test = CShort(CStr(Me.DataGridView3.CurrentCell.Value)) 'Test for number values
            Catch ex As Exception
                MessageBox.Show("Invalid Weight")
                Exit Sub
            End Try
        End If
    End Sub

    Private Sub DataGridView3_DataError(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewDataErrorEventArgs) Handles DataGridView3.DataError

        'do nothing

    End Sub

[jmcilhinney]

You shouldn't be using CellLeave. You should be using CellValidating.

Also, to ensure that a string is a valid representation of a number you should not be converting and catching exceptions on failure. You should be calling the TryParse method of the appropriate numeric type. If the number needs to be a valid Short then use Short.TryParse.

[MechEng]

Thanks for the quick reply. I am not familiar with the TryParse method, so I have some LIB reading to do. Thanks.

[MechEng]

Well, I should not have marked this as resolved so quickly.

When using CellValidating, the TryParse method can not be tested because the cell contents do not exist yet... unless there is a way to read the grid cell contents before the cell is validated. This being the case, there is no point in handling the CellValidating event at all, because the default Grid DataError event will fire if the CellValidating process fails to meet the requirements of the DataTable. Here is the code I am trying now. Am I still missing the bigger picture or is is simply trapping the Grid DataError the correct procedure?
Thanks

    Private Sub DataGridView3_CellValidating(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewCellValidatingEventArgs) Handles DataGridView3.CellValidating
        'Check for number values only in the Weight cell.

        If Me.DataGridView3.CurrentCell.ColumnIndex = 2 Then
            Dim singleVal As Single
            Dim result As Boolean
            Dim str_testString As String = ""

            If Not Me.DataGridView3.CurrentCell.Value Is Nothing And Not IsDBNull(Me.DataGridView3.CurrentCell.Value) Then
                str_testString = CStr(Me.DataGridView3.CurrentCell.Value)

                result = [Single].TryParse(str_testString, singleVal)
                Console.WriteLine(result & ", " & singleVal.ToString())

                If result = False Then
                    MessageBox.Show("Invalid Weight")
                    e.Cancel = True
                End If
            End If
        End If
    End Sub

    Private Sub DataGridView3_DataError(ByVal sender As Object, ByVal e As System.Windows.Forms.DataGridViewDataErrorEventArgs) Handles DataGridView3.DataError

        MsgBox("Error Trapped")

    End Sub