Exception when adding a new row from the RowLeave event - vb.net

Question

I have an unbound datagridview, set the option to allow user to add row to True, and all I want is that once I "complete" a row, the datagridview automatically should create a new empty row, so I set the method
DataGridView1.Rows.Add()
in the DataGridView1_Leave event, but once the row is finished and exception comes out:
An unhandled exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll - Unable to complete this operation in this event handler
What does it mean? It should be plain simple code, but I don't know how to solve
Here is the situation:
That's the recipient DataGridView. When I'm on the first blank row (which is created by the AllowUserToAddRow = true) and I press F3 a modal form is opened with another DataGridView containing products to select
and here's the code for the KeyDown event in the recipient DataGridView
Private Sub DataGridView1_KeyDown(sender As Object, e As KeyEventArgs) Handles DataGridView1.KeyDown
If e.KeyCode = Keys.F3 Then
If frmZoomArticoli.ShowDialog = Windows.Forms.DialogResult.OK Then
Dim codart As String = frmZoomArticoli.DataGridView1.CurrentCell.Value.ToString()
RicercaxCodiceArticolo(codart)
End If
End If
End Sub
Here the sub RicercaxCodiceArticolo(codart) which fills the recipient DataGridView with the selected product:
Private Sub RicercaxCodiceArticolo(ByVal codiceart As String)
Dim strsql As String
Dim cmd As SqlCommand
Dim source As New BindingSource
'Dichiariamo le variabili che ospitano i dati di riga
Dim codice As String
Dim descrizione As String
Dim unitamisura As String
Dim quantita As Double = 1.0
Dim codiceiva As Double
Dim costobase As Double
Dim prezzobase As Double
Dim costoultimo As Double
Dim giacenza As Double
Dim sconto1 As Double
Dim sconto2 As Double
connection.Open()
strsql = "SELECT CODICEARTICOLO AS 'Codice', DESCRIZIONEARTICOLO AS 'Descrizione', UNITAMISURA AS 'Um', CODICEIVA AS 'Iva' " _
& ", COSTOBASE AS 'Costo', PREZZOBASE AS 'Prezzo', SCONTO1 As 'Sc1', SCONTO2 As 'Sc2', COSTOULTIMO AS 'CostoUlt' " _
& ", BARCODE AS 'Barcode', NOTEARTICOLO AS 'Note' ,CATEGORIAARTICOLO AS 'Categ.Art.', GIACENZA AS 'Giacenza' " _
& ", FORNITOREPREF AS 'Fornit. Pref.' FROM Articoli " _
& " WHERE CODICEARTICOLO = '" & codiceart & "'"
cmd = New SqlCommand()
cmd.CommandText = strsql
cmd.CommandType = CommandType.Text
cmd.Connection = connection
source.DataSource = cmd.ExecuteReader()
'Assegniamo i dati letti nel bindingsource alle variabili
codice = source.Current!Codice
descrizione = source.Current!Descrizione
unitamisura = source.Current!Um
codiceiva = Convert.ToDouble(source.Current!Iva)
costobase = Convert.ToDouble(source.Current!Costo)
prezzobase = Convert.ToDouble(source.Current!Prezzo)
costoultimo = Convert.ToDouble(source.Current!Costoult)
giacenza = Convert.ToDouble(source.Current!Giacenza)
sconto1 = Convert.ToDouble(source.Current!Sc1)
sconto2 = Convert.ToDouble(source.Current!Sc2)
'Riempiamo le celle con i dati estratti dal BindingSource
With DataGridView1.CurrentRow
.Cells("grdCodice").Value = codice
.Cells("grdDescrizione").Value = descrizione
.Cells("grdUM").Value = source.Current!Um
.Cells("grdQuantita").Value = quantita
If TipoMovimento = "Carico" Then
.Cells("grdPrezzoUnitario").Value = source.Current!CostoUlt
Else
.Cells("grdPrezzoUnitario").Value = source.Current!Prezzo
End If
.Cells("grdSconto1").Value = sconto1
.Cells("grdSconto2").Value = sconto2
.Cells("grdSconto3").Value = 0.0
.Cells("grdSconto4").Value = 0.0
'Per calcolare il prezzo totale di riga dobbiamo tenere presente le
'informazioni che abbiamo gia' in anagrafica, ovvero il costo/prezzo
'e gli sconti
'Blocco di controllo sul tipo movimento
If TipoMovimento = "Carico" Then
If sconto1 > 0 Then
.Cells("grdPrezzoTotale").Value = quantita * (costoultimo * (costoultimo * sconto1 / 100))
Else
.Cells("grdPrezzoTotale").Value = quantita * costoultimo
End If
ElseIf TipoMovimento = "Scarico" Then
If sconto1 > 0 Then
.Cells("grdPrezzoTotale").Value = quantita * (prezzobase * (prezzobase * sconto1 / 100))
Else
.Cells("grdPrezzoTotale").Value = quantita * prezzobase
End If
End If
.Cells("grdAliquotaIva").Value = codiceiva
End With
connection.Close()
End Sub
and that's the result in the recipient DataGridView:
now, suppose that I don't want to edit the selected row because I don't need to edit quantity, or price, or whatever, but I just want to insert a new row to keep inserting other products. When I tab until the end of the row I want to create a new row, and that's why I wrote the DataGridView1.Rows.Add() in the RowLeave event of the DataGridView, but that's where the exception occurs:
I'm sorry for all the descriptions are in italian, but if you need any other details feel free to ask.
If there's nothing I can do all that remains is to add a button outside the DataGridView which adds a new row from there. Any other solution is welcomed.

Answer 1

Is there some reason you do not use a DataSource for the grid? Then you could simply add the row to the DataSource.
If you insist on manually adding the rows, then the problem you currently have is that the code is never “adding” a new row to the grid. The code simply uses the grids CurrentRow to set the values. This may work but the grids “new” row will not get created.
It is questionable to use the grids CurrentRow in this manner... So instead of using the grids CurrentRow for this, I suggest you “add” a new row in the RicercaxCodiceArticolo method. Something like below should add the new row and the “new-new” empty row should be at the bottom…
Dim newRowIndex As Int32
newRowIndex = DataGridView1.Rows.Add()
With DataGridView1.Rows(newRowIndex)
.Cells("grdCodice").Value = codice
.Cells("grdDescrizione").Value = descrizione
'.....
End With