How to catch this exception? [2003]

Tricky one. I downloaded this project from MSDN, DownloadManagerRefactored. I needed it because I need to display ComboBoxes in a datagrid.

Things are great except I am unable to edit my textboxes when the dataGrid is set to Readonly. So fine I set the dataGrid to ReadOnly = False, but then I get the new and blank record. This is what messes me up. If I click anywhere on the new record, I get an untrappable error (see pic).

This is no good because even though I can kind of "hide" it, the user can still hit the [Enter] key while editing the last row and that sets focus on the last row and the same thing happens.

I may be able to trap the columns under the Labal and/or ComboBox, but not the TextBox. I can upload the project but you won't be able to see it in action because it is database driven. I can post the main code that sets it up:

VB Code:

Private Sub BindControls()
 
            Dim strTestName As String
            Dim strColumnName As String
            Dim intColumntype As Integer
            Dim i As Integer
            Dim strCol As String
            Dim strDropdownValue As String
            Dim strSerialNumber As String
 
            Dim strCol1 As String
            Dim strCol2 As String
            Dim strCol3 As String
 
            MyConnection = New SqlConnection
            MyConnection.ConnectionString = cmbxSQLConnectionString.Text
            MyConnection.Open()
 
            MyCommand = New SqlCommand("spIASGetTest", MyConnection)
            MyCommand.CommandType = CommandType.StoredProcedure
            MyCommand.Parameters.Add("@testName", SqlDbType.VarChar).Value = cmbxLabTests.Text
            MyDataReader = MyCommand.ExecuteReader()
 
            Dim dmTable As New DataTable
 
            If MyDataReader.HasRows Then
                '
                While (MyDataReader.Read())
                    '
                    strTestName = MyDataReader.Item("Test Name")
                    strColumnName = MyDataReader.Item("columnName")
                    '
                    dmTable.Columns.Add(New DataColumn(strColumnName, GetType(String)))
                    '
                End While
                '
            End If
            '
            MyDataReader.Close()
 
            Dim dst As New DataGridTableStyle
 
            dmTable.TableName = strTestName
            dst.MappingName = strTestName
 
            ' Sample No
            strCol1 = dmTable.Columns.Item(0).ToString
            Dim dglcSampleNo As New DataGridLabelColumn
            dglcSampleNo.MappingName = strCol1
            dglcSampleNo.HeaderText = strCol1
            dst.GridColumnStyles.Add(dglcSampleNo)
            '
            '
            Dim dgcbc As DataGridComboBoxColumn
            Dim dgtbc As DataGridTextBoxColumn
 
            For i = 1 To dmTable.Columns.Count - 1
                '
                strCol = dmTable.Columns.Item(i).ToString
                '
                MyCommand = New SqlCommand("spIASGetDropDown", MyConnection)
                MyCommand.CommandType = CommandType.StoredProcedure
                MyCommand.Parameters.Add("@testName", SqlDbType.VarChar).Value = strTestName
                MyCommand.Parameters.Add("@columnName", SqlDbType.VarChar).Value = strCol
                '
                MyDataReader = MyCommand.ExecuteReader()
                '
                If MyDataReader.HasRows Then
                    '
                    dgcbc = New DataGridComboBoxColumn
                    dgcbc.MappingName = strCol
                    dgcbc.HeaderText = strCol
                    '
                    dgcbc.Add("")
                    '
                    While (MyDataReader.Read())
                        strDropdownValue = MyDataReader.Item("dropDownString")
                        dgcbc.Add(strDropdownValue)
                    End While
                    '
                    dst.GridColumnStyles.Add(dgcbc)
                    '
                Else
                    dgtbc = New DataGridTextBoxColumn
                    dgtbc.MappingName = strCol
                    dgtbc.HeaderText = strCol
                    dst.GridColumnStyles.Add(dgtbc)
               End If
                '
                MyDataReader.Close()
                '
            Next
 
            MyCommand = New SqlCommand("spIASGetSerialNumbers", MyConnection)
            MyCommand.CommandType = CommandType.StoredProcedure
            MyCommand.Parameters.Add("@projectName", SqlDbType.VarChar).Value = Me.txtProject.Text
            MyDataReader = MyCommand.ExecuteReader()
 
            Dim dr As DataRow
 
            If MyDataReader.HasRows Then
                '
                While (MyDataReader.Read())
                    '
                    strSerialNumber = MyDataReader.Item("serialNumber")
                    '
                    dr = dmTable.NewRow()
                    '
                    strCol1 = dmTable.Columns.Item(0).ToString
                    dr(strCol1) = strSerialNumber
                    '
                    For i = 1 To dmTable.Columns.Count - 1
                        strCol = dmTable.Columns.Item(i).ToString
                        dr(strCol) = "0"
                    Next
                    '
                    dmTable.Rows.Add(dr)
                    '
                End While
                '
            End If
 
            dataGrid.TableStyles.Add(dst)
            dataGrid.DataSource = dmTable
            dataGrid.ReadOnly = False
 
        End Sub

The problem is just like it says... you can't insert a NULL value when the table is expecting a number.... presumably it's one of the dropdown you've got there that's expecting a number, only nothing was sleected, so it tried to insert a NULL value instead....only that doesn't work.
You'll need to look to see what events fire off when... see if there's a before move, or something that fires before actually moving to a new row. From there you should be able to see everything going on, and validate your data before moving to the new row.

-tg

Nothing is wrong with the row that has values. The problem is I cannot trap this error - to find out exactly where it is occuring.

See the attached pic. The debugger sends me to the line of code "Public Class Mainform". I have stepped through almost all the dataGrid's events. Anything I do doesnt seem to matter. The debugger still sends me to that same line of code.

How can I "Try/Catch" that line of code?

Get an Application events file (from the project menu if you want).
The application event file has 4 (or 5) events that related to app startup, shutdown, and any exception thats thrown which is not handled.

Put your code there (if you want to messagebox it, or if you want to ignore it).
Note if you do choose to ignore it, an exception that occurs in any other part of the program (which is not handled by try/catch) will also be ignored.

Masfenix, how do I see or get this file? Thanks!