How set required field only if list get values ?

[Boris Demain]

Hi, 

I want to set a list field required only if his context list have some values. It's for creating and edditing issu.

I would use behavior but I don't found operation to check the fullness of my field.

Can some one helpe me ?

Thanks

[Rilwan Ahmed]

Any field is displayed on view screen only if it has value on it. 

[Boris Demain]

It's not my question...

When I create an issue, my field "Application" (list field) can have values or not. I would to set it as required only when it has value. Same thing for edditing screen