How do i make a field required for parent issues only

[Matt]

I would like to make the due date a required field but only for parent issues. 
I guess this can be done using groovy script on the validators in the workflow, but i am not sure how to go about this. 

[Peter Bengov · Accepted solution]

If you parent and child issues don't share the same Field Configuration, it's better to do so by setting the Due Date field as mandatory there, which will apply from ticket creation. 

Otherwise, you can use a validator, as you've mentioned. A Groovy script that you can use:

issue.issueTypeObject.name != "name of child task" || 
(issue.issueTypeObject.name == "name of child task" && issue.getDueDate() != null)

[Matt]

thanks guys 

[MJ]

Parent and child issues ordinarily are different issue-types.
As such, with the page Associating Field Behavior with Issue Types you should be able to configure different behaviors for fields depending on the issue-type they are placed under.