I have business object B1 which has an attribute which is of type of another business object B2. One allowed only, or undefined.
In a form for B1, there is a drop list of B2 objects the user can select, plus undefined.
Selecting a B2 object in the list requires some attributes of the old B2 object to be reset.
The user can therefore modify the B1 attribute by:
Going from an Undefined state to a B2 object
Going from one B2 object to another B2 object
Going from one B2 object to an Undefined state
So the question is, how to access in a rule the old B1.attribute to change the values and check whether it is Undefined or defined?
I tried OLD_VALUE() IS DEFINED, but it returns a syntax error.
Version 5.7
