Datagridview Validation & Ändern der Zellenwert

Question

Ich möchte eine Zelle in meinem Datagridview manipulieren, wenn es die Validierung, so dass, wenn der Benutzer einen Wert eingibt, der nicht gültig für die Datenbank ist, ist jedoch leicht auf gültige Daten umgewandelt werden, wird das Programm den Wert auf eine entsprechende Änderung ein.

Ich bin in der Lage meinen Wert richtig zu überprüfen, aber wenn ich versuche, es gilt, etwas zu ändern, erhalte ich eine Dataerror. Hier ist mein Code:

        private void unit_List_2_GroupsDataGridView_CellValidating(object sender, DataGridViewCellValidatingEventArgs e)
    {
        Console.WriteLine("Validating");
        DataGridViewColumn col = this.unit_List_2_GroupsDataGridView.Columns[e.ColumnIndex];
        DataGridViewCell cell = this.unit_List_2_GroupsDataGridView.Rows[e.RowIndex].Cells[e.ColumnIndex];
        if (col == this.batchDataGridViewTextBoxColumn && this.unit_List_2_GroupsDataGridView.IsCurrentCellInEditMode)
        {
            Console.WriteLine("   Batch Column");
            DataRow[] rows = label_EntryDataSet.viewJobBatchList.Select(String.Format("Job={0} AND Display='{1}'"
                , comboBox1.SelectedValue, e.FormattedValue));
            if (rows.Length == 1)
            {
                Console.WriteLine("      Auto Completed item from list: {0}", rows[0]["Batch"]);
                //e.Cancel = true;
                cell.Value = rows[0]["Batch"];
                //this.unit_List_2_GroupsDataGridView.EndEdit();
            }
            else
            {
                Console.WriteLine("     No Autocomplete!");
                int i = 0;
                if (!int.TryParse(e.FormattedValue.ToString(), out i))
                {
                    Console.WriteLine("         Not an integer either");
                    e.Cancel = true;
                }
            }
        }
    }

Die Zeile, die liest cell.Value = Reihen [0] [ "Batch"];. sind nicht zu tun, was ich erwarte, dass es tun

Answer 1

The CellValidating event occurs just prior to when the DataGridView leaves edit mode; it's an event that relates-to/involves the editing control (DataGridView.EditingControl). You should never attempt to change the cell value in the handler for this event, because unless you cancel the event (in which case the user is stuck in edit mode), the cell value is set to the value from the editing control immediately after the event finishes. This, therefore, undoes any action you perform in the handler.

What you have to do instead is change the value in the editing control (remembering not to cancel the event). For example, for a DataGridViewTextBoxCell, you would use the following instead of your problematic line:

unit_List_2_GroupsDataGridView.EditingControl.Text = Convert.ToString(rows[0]["Batch"]);

You should find that this solves your issue.

Answer 2

In general, it is better to use the CellParsing event whenever you need to convert/change the value in a cell. From within that event, you can indicate that the user's value is invalid by setting the ErrorText value of the cell or row.