InvalidateFieldChoiceList example

In the following example, a Defect record type has the two fields product (a reference to the Product record type) and owner (a reference to User). Each Product record type has a field called contributors (a reference list to User).

In order for the owner choice list field to be updated whenever the value for Product is changed, you can use the InvalidateFieldChoiceList method, instead of using the Recalculate Choice List option. See Performance considerations for using hooks for more information.

For example, in the Defect record type, you add a value changed hook for the field product,

Perl

sub product_ValueChanged {
    my($fieldname) = @_;
    # $fieldname as string scalar
    # record type name is Defect
    # field name is product
    # Make sure that the choice list for owner is based on
    # this new value for product.
    $entity->InvalidateFieldChoiceList("owner");
	}

and you add a choice list hook for the field owner


sub owner_ChoiceList 
{
    my($fieldname) = @_;
    my @choices;
    # $fieldname as string scalar
    # @choices as string array
    # record type name is Defect
    # field name is owner
    # Is the value of product set?  If not, return an empty list.
    my $productFieldInfo = $entity->GetFieldValue("product");
    return @choices unless
    $productFieldInfo->GetValidationStatus() == $CQPerlExt::CQ_KNOWN_VALID;
    return @choices unless $productFieldInfo->GetValue() ne "";
    # Field product is set and valid.
    # Get the list of contributors on this product.
    @choices = $entity->GetFieldValue("product.contributors")
                      ->GetValueAsList();
    return @choices;
}

VBScript

Sub product_ValueChanged(fieldname)
  ' fieldname As String
  ' record type name is Defect
  ' field name is product
	InvalidateFieldChoiceList "owner"
End Sub

and you add a choice list hook for the field owner

Sub owner_ChoiceList(fieldname, choices)
  ' fieldname As String
  ' choices As Object
  ' record type name is Defect
  ' field name is owner
    ' Is the value of product set?  If not, return an empty list.
	Dim productFieldinfo
	set productFieldinfo = GetFieldValue("product")
	if productFieldinfo.GetValidationStatus() <> AD_KNOWN_VALID then exit sub
	productFieldInfovalue = productFieldinfo.GetValue()
	if productFieldInfovalue = "" then exit sub

    ' Field product is set and valid.
    ' Get the list of contributors on this product.
	Dim productFieldvalues
	productFieldvalues = GetFieldValue("product.contributors").GetValueAsList()
	for each contributor in productFieldvalues
		choices.AddItem contributor
	next

End Sub

Each time you start an action, owner_ChoiceList is run once, and every time you change product, the owner choice list is marked as not valid. The user interface then requests the choice list, which forces the choice list hook to be re-executed.