private void cboRegionZone_SelectedIndexChanged(object sender, EventArgs e) { CADASTRAL_ZONE cadastreZone = cboRegionZone.SelectedItem as CADASTRAL_ZONE; if (cadastreZone != null && cadastreZone.ID_CADASTRAL_ZONE != -1) { List <CADASTRAL_REGION> regions = _basicService.LoadAllCADASTRAL_REGION(_businessParam).Where(c => c.ID_CADASTRAL_ZONE == cadastreZone.ID_CADASTRAL_ZONE).OrderBy(c => c.NAME).ToList(); regions.Insert(0, new CADASTRAL_REGION { NAME = "---", CODE = "", ID_CADASTRAL_REGION = -1 }); cboRegion.DataSource = regions; cboRegion.DisplayMember = "NAME"; cboRegion.ValueMember = "ID_CADASTRAL_REGION"; txtCodeRegionZone.Text = cadastreZone.CODE; if (regions == null || regions.Count == 0) { txtCodeRegion.Text = ""; txtCodeMunicipality.Text = ""; txtCodeTerriturialUnit.Text = ""; cboRegion.DataSource = null; cboMunicipality.DataSource = null; cboTerritorialUnit.DataSource = null; } txtCodeRegionZone.ReadOnly = true; } else { cboRegion.DataSource = null; txtCodeRegionZone.ReadOnly = false; txtCodeRegionZone.Text = ""; } }