Trigger "Create a sub-task" from a subtask

[Aleksandr Serebriakov]

Hello,

We have Parent_Issue_#1 working by Workflow_#1 (if workflow maters).

Parent_Issue_#1 has Sub-task_#1. Sub-task_#1 works by Workflow_#2 (if workflow maters).

We have to create a Sub-task_#2 for Parent_Issue_#1.
"Create a sub-task" have to be triggered from Sub-task_#1 on one of its workflow (Workflow_#2) transition.

Result should look like:

Parent_Issue_#1
   └ Sub-task_#1 (creates Sub-task_#2 at one of its workflow transitions)
   └ Sub-task_#2

We try to achieve it via ScriptRunner scripted post-function.

How can I point at parent issue to be able to create a sub-task in my case?

Edited (removed some code because understood it was wrong).

[Aleksandr Serebriakov · Accepted solution]

Managed to do what i need:

import com.atlassian.jira.component.ComponentAccessor
import com.atlassian.jira.issue.Issue
import com.atlassian.jira.issue.MutableIssue

def issueFactory = ComponentAccessor.getIssueFactory();
def constantManager = ComponentAccessor.getConstantsManager();
def issueManager = ComponentAccessor.getIssueManager();
def subTaskManager = ComponentAccessor.getSubTaskManager()
def user = ComponentAccessor.getJiraAuthenticationContext().getUser()

Issue parentIssue = issue.getParentObject();
MutableIssue newSubTask = issueFactory.getIssue();

newSubTask.setSummary('BOOO-512');
newSubTask.setParentObject(parentIssue);
newSubTask.setProjectObject(parentIssue.getProjectObject());
newSubTask.setIssueTypeId(constantManager.getAllIssueTypeObjects().find{
 it.getName() == "Sub-task"
 }.id)
Map<String,Object> newIssueParams = ["issue" : newSubTask] as Map<String,Object>
 issueManager.createIssueObject(user.directoryUser, newIssueParams)
 subTaskManager.createSubTaskIssueLink(parentIssue, newSubTask, user.directoryUser)

Thanks to the code provided by Thanos Batagiannis: https://community.atlassian.com/t5/Answers-Developer-Questions/Hi-Can-any-one-guide-me-how-to-create-Subtasks-in-post-function/qaq-p/493429 

[Tayyab Bashir]

Hi, You can do that with Bob Swift - Create on Transition add-on. 
I ScriptRunner doesn't let you create a sub-task from a subtask transition.