Need a simple way to get id of ReferenceField

[anti-social]

Sometimes I need to get reference field id but way I do this is ugly. As I understand if I get value of reference field there will be additional query to mongo.

So I need to write something like that:

class MyDoc(Document):
    other_doc = ReferenceField('AnotherDoc')

d = MyDoc.objects(id=object_id).first()
other_doc_dbref = d._data.get('other_doc')
other_doc_id = other_doc_dbref.id if other_doc_dbref else None

I think this should be easier.