// Precondition: Focus shifting from one of the address combo boxes
// sender is ComboBox
// Postcondition: If no address selected, focus remains and error provider
// highlights the field
private void listBoxSelectAddress_Validating(object sender, CancelEventArgs e)
{
// Downcast to sender as ComboBox, so make sure you obey precondition!
ListBox lstBo = sender as ListBox; // Cast sender as combo box
bool valid = true; // bool for testing
if (listBoxSelectAddress.SelectedIndex == -1)
{
e.Cancel = true; // Stops focus changing process
// Will NOT proceed to Validated event
valid = false;
}
else
{
lstBo = listBoxSelectAddress;
}
if (!valid) // error message if not valid
{
e.Cancel = true; // Stops focus changing process
// Will NOT proceed to Validated event
NoAddressError.SetError(listBoxSelectAddress, "You must select an address.");
MessageBox.Show("You must select an address.", "Error");
}
}
// Precondition: Validating of sender not cancelled, so data OK
// sender is Control
// Postcondition: Error provider cleared and focus allowed to change
private void listBoxSelectAddress_Validated(object sender, EventArgs e)
{
// Downcast to sender as Control, so make sure you obey precondition!
Control control = sender as Control; // Cast sender as Control
// Should always be a Control
NoAddressError.SetError(control, "");
}
