Is there a way to use Okta Expression Language in a filter or search

I have a custom field in the profile which is an array.

I want to get all the users whose ‘custom_field’ is not empty.

Something like:

Is this possible?

It isn’t possible.

You can check the presence of a value by:
{{url}}/api/v1/users?limit=25&search=profile.custom_field pr

This will only work if the value is not null, though. I think this is an awesome enhancement request, can you log an idea here: