Getaroom API

All of these answers seem to point to how to SET the value of a custom field despite the original question asking how to GET the value of a custom field. This is the closest forum I've found regarding the issue I have but it also looks like many moderator's comments have been redacted and URLs are no longer valid. As far as I can tell, the following approach seems like the most appropriate endpoint for the .get method of the ZAFClient initialized object.

client.get('ticketFields:custom_field_123456789').then(function(data) {
  console.log(data);
}

yields:

{
  hasOptions: boolean,
  isEnabled: boolean,
  isVisible: boolean,
  label: "Name of Field",
  name: "custom_field_123456789",
  requireOnStatuses: Array [],
  type: "regexp",
}

How do you get the actual value of the field? Is there another way to go about getting the value of a custom field and I'm just not seeing it in the docs?