Use validation to prevent issue creation based on parent's custom field value

[Bryan McMillan]

I am looking to implement a system of Toll Gates.  I want to prevent the creation of a child issue (not sub-task) unless the parent's Toll Gate (custom field) is set to a certain value.  I've looked at and tried the Workflow Toolbox's solutions, a project property will not suffice, looked through the blogs and such.  Has anyone ever tried implementing a simple Toll Gate system to enforce quality within a validation rule?

Thanks much in advance

[Bob Swift OSS (Bob Swift Atlassian Apps)]

I think a Conditioned validator (Update on Transition for JIRA add-on) on the create issue transition could be configured to do this. You need a JQL query to determine the parent key (your definition of parent) and use the result as the first parameter of the fieldValue function substitution variable and Toll Gate as the second parameter. Use that as part of the condition for the creation of the issue.