DataGridView CellValidated Event triggers when closing form

Question

Situation: I have placed a DataGridView on a form. In the DataGridView-Object I do checks on some cells - like for example if the amount which was entered by the user is not greater than 100. The checks will be performed when the user leaves the cell with Enter, Tab or the Arrow Keys.

Problem: Everything is working fine but when the cursor is in the cell and the value is greater than 100 and the User presses the "X"-Button on the form (Close-Button) the Message still appears.

Question: How can I prevent the appearance of the MessageBox when the User is clicking on the X-Button on the form?

Code Samples:

private void dgv_CellValidated(object sender, DataGridViewCellEventArgs e)
        {
            try
            {
                const int nColumn = 2;
                if (!e.ColumnIndex.Equals(nColumn))
                {
                    return;
                }

                if (e.ColumnIndex.Equals(nColumn))
                {
                    double nMengeSource;
                    double.TryParse(dgv.Rows[e.RowIndex].Cells[fldMenge.Name].Value.ToString(),
                        out nMengeSource);

                    double nMengeLos;
                    double.TryParse(dgv.Rows[e.RowIndex].Cells[fldMengeLos.Name].Value.ToString(),
                        out nMengeLos);

                    // prüfe ob erfasste Menge die Menge im Los überschreitet
                    if (nMengeSource > nMengeLos)
                    {
                        var sMsg = String.Empty;
                        sMsg += "Warning! Value is greather than allowed!";
                        MessageBox.Show(sMsg, "Check...", MessageBoxButtons.OK, MessageBoxIcon.Information);
                    }
                }
            }
            catch (Exception ex)
            {
                Dialog.SetDefaultCursor();
                MessageBox.Show(MethodBase.GetCurrentMethod().Name + @"\n\n" + ex + @"\n\n" + ex.Message);
            }
        }

Why would you want to? Isn't that value still going to be stored, and isn't it still invalid? — DonBoitnott
Well, if the user clicked on "X" I do not want to validate that value anymore . On the form there is another button called "Save" - if the user clicked on the "X"-Button on the form he does not want to save his/her entered value... "X" should be interpreted as "Cancel"... — HNITC

OhBeWise OhBeWise · Accepted Answer · 2015-05-20T17:57:31

By clicking X, the DataGridViewCell loses focus, which causes the validation on the cell to fire. You want to suppress this, but only when the Form is closing. However, you can't do this in Form.FormClosing because it is fired after validation has occurred. But you can do it with the following method:

protected override void WndProc(ref Message m)
{
  switch (((m.WParam.ToInt64() & 0xffff) & 0xfff0))
  {
    case 0xf060:
      this.dataGridView1.CausesValidation = false;
      break;
  }

  base.WndProc(ref m);
}

DataGridView CellValidated Event triggers when closing form

2 Answers