Need assistance on adding a script Listener

[Mahesh Babu Batta]

Can you please help me on how can I achieve following requirement.
We need to make two values as mandatory of multi value selection field only while editing or updating the ticket if the ticket is created with only single value while creating a ticket.

Thanks

[Nic Brough -Adaptavist-]

A listener is the wrong place to look.  A listener reacts to an event, after the event has happened.  The edit or transition is complete by the time a listener gets to look at it, too late for validation - the human has committed the data and the service stored it before the listener gets it.

You will need either a validator or a behaviour to do this check.  They both have weaknesses though - validators can only be run on transitions, and behaviours only run on-screen (so REST calls and internal automations can ignore them).  A combination of both might be the best option

I'm not sure how to do a behaviour, they're my weakest area in SR, but https://library.adaptavist.com/entity/set-behaviour-multi-and-single-select-options-and-value might have something you can re-use

If you go the validator route, some snippets can be found at https://library.adaptavist.com/search?page=1&products=jira&term=validator