JQL sub-query

Question

Hello. I am using Script Runner.

I am writing to ask you for a piece of advise. 
My ultimate goal is issuing a subquery.

I am trying to implement a custom JQL function. It's going to be called
filterQuery(). 
It's supposed to take 1 argument - some JQL query and return issues.

It's use-case is in the following example:
issuetype = epic and issuekey in filteryQuery("project = MYPROJ")

But unfortunately, it's impossible to use own functions with 'issuekey in'. But, when used with the IN or NOT IN operators, issueKey supports:
issueHistory()
linkedIssues()
votedIssues()
watchedIssues()

So, can I expand that list of functions about with my own one using Script Runner?
Thanks a lot.

Geert_Graat · Answer

I think you can do a lot of what you want with the already available JQL functions in Script Runner, for example:
jql2: project = IDS and issuetype = Epic AND issueFunction in linkedIssuesOf("project = CM", "
")
(I am not able to test this right now).
Also be sure to have a look at the complex examples, which show how you can use filters: https://jamieechlin.atlassian.net/wiki/display/GRV/Scripted+JQL+Functions#ScriptedJQLFunctions-MoreComplexExamples.

e_cvujr2 · Answer

Good to have jira function (let's name it like filterResult), that will add an ability to do subquery in JQL.
Example
jql1: project = CM
jql2: project = IDS and issuetype = Epic and linkedIssues in filterResult(jql1) - to show all issues in IDS project that have links to issues from CM project
jql3: project = CM and EpicLink in filterResult(jql2) and linkedIssues in filterResult("resolved < -2d") - for CM issues with epics from IDS, matching jql2 and linked with issues that was resolved less then 2 days ago.

e_cvujr2 · Answer

Basically, I am looking for subquery functionality in JQL. I think I need to write my own function here.