How to get parentIssueId for a sub-task with Behaviours (Script Runner)?

Question

According to the Behaviours documentation, one should be able to retrieve the ID of the parent issue of a sub-task in an initialiser script like this:

FormField parent = getFieldById("parentIssueId")

Am I doing something wrong as parent.value is always null?

An open issue SRJIRA-253: Cannot get parentIssueId value seems to perfectly capture what I'm experiencing. There are no comments on that issue or any other hints about what could be going wrong. Any hints or pointers would be highly appreciated.

I'm using Script Runner 3.1.4 on JIRA 6.4.1.

adammarkham · Accepted Answer

What you have above won't work in an initialiser but if its attached to a field it will work. Please see the answer here: https://answers.atlassian.com/questions/17894295

You can use:

underlyingIssue.parentId

Or to get the full issue object use:

underlyingIssue.parentObject