Can I hide or disable a transition in Jira based on a field having a value?

Question

Hi,

I'm trying to set up a workflow with a "provide estimate" step. This is a simple self-transition from the "open" state right back onto itself. The purpose is simply to provide the user a workflow button that says "Provide Estimate."

I would like to disable this transition if the user has already provided an estimate when initially creating the task. I can't figure out how to do this. It seems I can use conditions to make the transition button APPEAR if a certain field is filled out. But I can't figure out how to DISABLE the transition if a field is filled out.

Any help would be appreciated! We are using JIRA Cloud btw.

Gavin Carter1 · Answer

Thanks Udo. Had to change a little bit around but that gave me the clue I needed - using the value field condition. I also didn't realize that leaving the field blank produces "NULL" in the condition statement. I manually typed NULL into the compare box and spent several confused minutes trying to figure why it wasn't working 
 Landed here, thanks again -

The field Estimate will have to be equal to value 'NULL'. Compared as String.

Udo Brand · Answer

You can use the value field condition of JIRA Suite Utilities Plugin (preinstalled in JIRA Cloud). Simply add a condition like

The field <Field name> will have to be not equal to value 'NULL'. Compared as String.

Bob Swift · Answer

A Conditioned validator would be able to check that or more complex conditions. Part of Update on Transition for JIRA. That is only available for server version however.