Get _id field (predefined field) in Elasticsearch document

Hello. I’ve try to capture the “_id” field of Elasticsearch document in a Grafana variable. The preview always returns “None”. Other fields, like _type, @timestamp, or _index works. There is a special syntax for that field?
Thanks

Bye

Daniele

Schermata 2020-04-28 alle 14.43.04

It’s little bit difficult, unless you have a common key for “labels.job”: “blockchain” AND “name”: “eth_get_block”

Regards,
Fadjar Tandabawana