How to display last single value of boolean type using ElasticSearch datasource

Hello !

I’m trying to display the last single value of a boolean type using ElasticSearch datasource, but I can’t find a way to display it

In Visualization I’ve choosen “Single stat” and in “Value” -> “show”: “current”

Then in the Queries, my boolean field doesn’t appear in metrics. So I don’t know what Metrics function I have to choose ?
In the Group By section, I have tried “Terms” with “my boolean field name”, but It doesn’t always show me the last value (according to the order “top” or "bottom)

Can anyone one help me ?

Thanks by advance