How can I add a state transition validator to ensure that Priority is set?

[Mike Burton]

We have a default priority called "Unprioritized". I would like to ensure that the priority is set to any other value (besides Unprioritized) when a ticket transitions to another state.

The way I've done this for other fields was to use a "Field Required Validator" to require that the field has been set. However, in this case the field is already set, just not to a useful value. For other fields, you can generally make them optional, in which case the Field Required Validators works fine, but that doesn't seem to be an option for the Priority field.

How can I ensure my users set the priority on a state transition?

[Dave Theodore [Coyote Creek Consulting]]

Best practices would be to not have the "Unprioritized" Priority and leave the field blank when things are not prioritized. Given that you have things set up the way you do, probably the best solution would be to use the JIRA Workflow Toolbox app. (Hopefully you're not on Cloud.) You should be able to make the regexp Validator do what you need. 

I'd recommend eliminating the Unprioritized Priority and leaving the field blank, though. It would be easy to do this with a Bulk Edit, then delete the Priority.

[Mike Burton]

Afaik it does not appear to be possible to set a blank priority: https://community.atlassian.com/t5/Jira-questions/How-do-define-a-blank-or-non-selected-Priority-Field-Value/qaq-p/224401

[Mike Burton]

One work around is to use a condition instead of a validator, but that is a confusing user experience because it means that the transition button is hidden and users may not know why. Also, it makes drag-and-drop impossible on scrum boards since it hides the target status.