I was asked by one of our customers to help them find a way, how to add special validator to their workflow in Jira cloud - they needed to check, whether all the tasks in Epic are done, before it can be closed too.
After a little bit googling I found out this can be done via Jira Expressions.
With Jira Expressions you have basically two options:
- build your own forge app
- install some application, which enables you to add Jira Expressions validators
I didn’t want to build an app for this one specific use-case and I also didn’t want to force our customer to buy complex application like ScriptRunner or JWT.
Then my colleague @[deleted](thank you!) suggested to try Workflow Building Blocks for Jira. Normally I don't consider such solutions (apps without reviews and with only a few installs), but I gave it a go... and I was suprised how easily I achieved what I wanted:
- I edited my workflow for Epic and selected Linked Issues Validator (WBB) at the Validators tab
- At the Children tab I selected I want to have children in the status category Done, which generated Jira expression

- I also used validator tester on several Epics to check the results

- I added validator to the workflow.

Done! Easy, no-code...
Application is free right now and has a lot more possibilities related to workflow conditions and validators, see the documentation.
(Please, be aware I'm not in touch with the vendor of the application, I was just happy to find the solution for the problem!)