To create a subtask only if one does not already exist for the respective parent issue can be achieved using the app Create On transition. If subtask doesn't already exist for the parent issue, then adding the below post function will create a subtask else it will not generate the subtask at the time of transition of the workflow.
Instructions
Steps to create a post-function for this scenario.
- Go to the Cogwheel and click on Issues.
- Under the Workflows section, select the workflow to click on Edit link.
- Now select the transition steps to add the post- function.
4. Click on Add Post Function link and then select Create Sub-task option. After this click on Add button.
5. Now add the below Post Function:
Create Sub-task Conditions: Ignore if original issue is a sub-task Condition value: %jql_result_count%, Regex pattern: 0 Summary: %parent_summary%:sub-task Description: Issue type: Sub-task (10003) Priority: Parent's priority Reporter: Current user Assignee: Parent issue's assignee Affected versions: None Fixed versions: None Components: Parent issue's components JQL query: parent= %original_key%
6. Publish the workflow and rerun the scenario.
Add the above Post Function in your Dev/Staging environment first and then implement it in the Production environment.