Concurrency Error when record is deleted by another user

[StacyOW]

Ok I have been trying to handle some of the concurrency errors on my winforms app. When the database record has changed and the user tries to save it gives a popup with a choice to overwrite or cancel basically.

My problem is if the record was deleted by another user and they try to save changes to it I get this error...


This is what I have for my saving code right now. In the Save() function I tried to catch that NullException and just tell the user that record has already been deleted by another user, but it doesn't work.

I have a save button that runs this code...

  Private Sub PordersBindingNavigatorSaveItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PordersBindingNavigatorSaveItem.Click
        Me.Validate()
        Me.PordersBindingSource.EndEdit()
        Me.ItemsBindingSource.EndEdit()
        Me.PoinvoiceBindingSource.EndEdit()
        If Me.Save() Then
            MsgBox("Your purchase order changes were saved.")
        End If

    End Sub

Then the Save() Function that runs this code...

   Private Function Save() As Boolean
        Dim saved As Boolean = False

        If Me.PordersItemsDataSet.HasChanges Then
            Try

                Dim pordersUpdates() As DataRow = Me.PordersItemsDataSet.porders.Select("", "", DataViewRowState.Added Or DataViewRowState.ModifiedCurrent)
                Dim itemsUpdates() As DataRow = Me.PordersItemsDataSet.items.Select("", "", DataViewRowState.Added Or DataViewRowState.ModifiedCurrent)
                Dim invoiceUpdates() As DataRow = Me.PordersItemsDataSet.poinvoice.Select("", "", DataViewRowState.Added Or DataViewRowState.ModifiedCurrent)

                UpdateDatabasePorders()       ' Me.PordersTableAdapter.Update(pordersUpdates)
                UpdateDatabaseItems()         ' Me.ItemsTableAdapter.Update(itemsUpdates)
                UpdateDatabaseInvoice()       ' Me.PoinvoiceTableAdapter.Update(invoiceUpdates)

                Dim pordersDeletes() As DataRow = Me.PordersItemsDataSet.porders.Select("", "", DataViewRowState.Deleted)
                Dim itemsDeletes() As DataRow = Me.PordersItemsDataSet.items.Select("", "", DataViewRowState.Deleted)
                Dim invoiceDeletes() As DataRow = Me.PordersItemsDataSet.poinvoice.Select("", "", DataViewRowState.Deleted)

                Try
                    Me.PoinvoiceTableAdapter.Update(invoiceDeletes)
                Catch dbcx As System.NullReferenceException
                    MsgBox("This record has already been deleted by another user.")
                Catch ex As Exception
                    MsgBox("An error was thrown while attempting to update the Invoice Table.")
                End Try                Me.ItemsTableAdapter.Update(itemsDeletes)
                Me.PordersTableAdapter.Update(pordersDeletes)

                saved = True

            Catch ex As Exception
                MsgBox(ex.ToString)
            End Try
        End If

        Return saved

    End Function

These subs are for when it runs the UpdateDatabasePorders. They look basically the same for UpdateDatabaseItems and UpdateDatabaseInvoice.

    Private Sub UpdateDatabasePorders()
        Try
            Me.PordersTableAdapter.Update(Me.PordersItemsDataSet.porders)
            'MsgBox("Update successful on Purchase Orders Table")

        Catch dbdel As System.NullReferenceException
            MsgBox("This record was deleted by another user.")

        Catch dbcx As Data.DBConcurrencyException
            Dim response As Windows.Forms.DialogResult

            response = MessageBox.Show(CreateMessagePorders(CType(dbcx.Row, PordersItemsDataSet.pordersRow)),
                "Concurrency Exception", MessageBoxButtons.YesNo)

            ProcessDialogResultPorders(response)

        Catch ex As Exception
            MsgBox("An error was thrown while attempting to update the Purchase Orders Table.")
        End Try
    End Sub

    Private Function CreateMessagePorders(ByVal crp As PordersItemsDataSet.pordersRow) As String
        Return "Database: " & GetRowDataPorders(GetCurrentRowInDBPorders(crp),
                                         Data.DataRowVersion.Default) & vbCrLf &
               "Original: " & GetRowDataPorders(crp, Data.DataRowVersion.Original) & vbCrLf &
               "Proposed: " & GetRowDataPorders(crp, Data.DataRowVersion.Current) & vbCrLf &
               "Do you still want to update the database with the proposed value?"
    End Function


    '--------------------------------------------------------------------------
    ' This method loads a temporary table with current records from the database
    ' and returns the current values from the row that caused the exception.
    '--------------------------------------------------------------------------
    Private TempPordersDataTable As New PordersItemsDataSet.pordersDataTable

    Private Function GetCurrentRowInDBPorders(
        ByVal RowWithError As PordersItemsDataSet.pordersRow
        ) As PordersItemsDataSet.pordersRow

        Me.PordersTableAdapter.Fill(TempPordersDataTable)

        Dim currentRowInDbPorders As PordersItemsDataSet.pordersRow =
            TempPordersDataTable.FindByPONum(RowWithError.PONum)

        Return currentRowInDbPorders
    End Function


    '--------------------------------------------------------------------------
    ' This method takes a pordersRow and RowVersion 
    ' and returns a string of column values to display to the user.
    '--------------------------------------------------------------------------
    Private Function GetRowDataPorders(ByVal custRow As PordersItemsDataSet.pordersRow,
        ByVal RowVersion As Data.DataRowVersion) As String

        Dim rowData As String = ""

        For i As Integer = 0 To custRow.ItemArray.Length - 1
            rowData &= custRow.Item(i, RowVersion).ToString() & " "
        Next

        Return rowData
    End Function

    Private Sub ProcessDialogResultPorders(ByVal response As Windows.Forms.DialogResult)
        Select Case response

            Case Windows.Forms.DialogResult.Yes
                PordersItemsDataSet.porders.Merge(TempPordersDataTable, True)
                UpdateDatabasePorders()

            Case Windows.Forms.DialogResult.No
                PordersItemsDataSet.porders.Merge(TempPordersDataTable)
                MsgBox("Update cancelled for Purchase Orders Table")
        End Select
    End Sub

Anyone have any idea how to handle the concurrency problem when the record is deleted by one user but still visible to another user until they refresh?

Thanks,
Stacy