Is there a way to ensure that multiply-valued Custom Fields (eg. a “Enter
multiple values” CF) don’t end up with duplicate entries?
What I’m trying to do more broadly: I have another ticketing system I’m
integrating with, and a single RT ticket can be associated with multiple
tickets in this other system. I’ve added its subject tag to
$ExtractSubjectTagMatch, but I also want to have an easy link to go visit
the other ticket. I’ve created a CF with the right URL pattern, and I’m
using a patched version of RT::Extension::ExtractCustomFieldValues to pull
the subject tags into the CF, but if a new message comes in which adds a
new subject tag, the earlier subject tags get added again.
I can further hack RT::Extension::ExtractCustomFieldValues to ensure
uniqueness on insertion, but this seems like something which might be
better enforced at the CF level (“Enter multiple unique values”). Is
there a way to do that? Or, is there a better way to solve my larger
problem of links to the other ticketing system?