How to create sub-task based on custom field value

Overview

This article explains how to create a sub-task using the app, Create on Transition's Create sub-task post function, based on a custom field value on the parent issue.

Instructions

Add a post-function in the workflow associated with the parent issue. To create the post function,

1. Log into Jira as an Administrator and click  > Issues.
   a) If there is a postfunction created already, update the postfunction in step#5 and move on from there.
   b) If there is no postfunction created already then follow the below steps:
2. Under the Workflows section, select the intended workflow and click the Edit link.
3. Select the transition to which you wish to add the post-function. Select the Post Functions option as shown below:
   
4. Click the Add Post Function link and select Create Sub-task from the available options.
5. Provide the below post function along with the Conditions:
       a) Provide the customfield id in the Condition value and their values in the Regex pattern as shown: 
   
6. Click Update and publish the workflow.
7. Once the post function is created for the transition, and if only the specified values are given for the custom fields, for example: Release and Release instance, the sub-task is created for the issue.