Script runner validator- reject the option for setting FieldA as long as the fieldB is empty

[Deleted user]

 I would like to reject the option for setting the FieldA ("Fixed in version/s") filed as long as the fieldB ("Affects Version/s") field is empty

should I work with ?

if (! cfValues['FieldA']) ...

how should I write it with script validator? 

Thanks for your help !

[Roland Holban (Adaptavist) · Accepted solution]

Instead of doing this in a validator, you could set up a behaviour and hide the fixedVersions field until the user inputs something in the affectsVersions field. 

Server-side script on "Affects Version/s" field:

def affectsVersions = getFieldById("versions")
def fixedInVersions = getFieldById("fixVersions")

if (!affectsVersions.value) {
    fixedInVersions.setHidden(true)
} else {
    fixedInVersions.setHidden(false)
}