What should the bucket path be with a top hits

[m.a.tanaka (Meang Akira Tanaka)]

I am trying to create a query in elasticsearch, which is able to retrieve the documents for each group, which is the latest document within each group and meet a specific criteria. But I have not been able to solve this one.

Say the following documents are indexed in myindex in elasticsearch:

POST /myindex/_bulk
{ "index":{} }
{ "objid": 1, "ident":"group1","version":1, "chdate": 1, "field1" : 1}
{ "index":{} }
{ "objid": 2, "ident":"group1","version":2, "chdate": 2, "field1" : 0}
{ "index":{} }
{ "objid": 3, "ident":"group1","version":2, "chdate": 3, "field1" : 1}
{ "index":{} }
{ "objid": 4, "ident":"group1","version":2, "chdate": 4, "field1" : 0}
{ "index":{} }
{ "objid": 5, "ident":"group1","version":3, "chdate": 1, "field1" : 0}

I would like to find all documents, which has field1 set to x if the document with the highest chdate, for each ident and version, which has field1 set to x.

In a case where x is 0 then the documents, which has objid 4 and 5 should be returned In a case where x is 1 then the documents, which has objid 1 should be returned

ChatGpt suggested this query:

{
  "size": 0,
  "aggs": {
    "ident": {
      "terms": {
        "field": "ident"
      },
      "aggs": {
        "version": {
          "terms": {
            "field": "version"
          },
          "aggs": {
            "top_hits_agg": {
              "top_hits": {
                "size": 1,
                "sort": [
                  {
                    "chdate": {
                      "order": "desc"
                    }
                  }
                ]
              }
            },
            "field1_filter": {
              "bucket_selector": {
                "buckets_path": {
                  "hits": "top_hits_agg.hits.hits",
                  "field1": "top_hits_agg.hits.hits._source.field1"
                },
                "script": {
                  "source": "params.field1 == 0"
                }
              }
            }
          }
        }
      }
    }
  }
}

But elasticsearch comes out with following error

{
  "error" : {
    "root_cause" : [
      {
        "type" : "action_request_validation_exception",
        "reason" : "Validation Failed: 1: No aggregation found for path [top_hits_agg.hits.hits._source.field1];"
      }
    ],
    "type" : "action_request_validation_exception",
    "reason" : "Validation Failed: 1: No aggregation found for path [top_hits_agg.hits.hits._source.field1];"
  },
  "status" : 400
}

Anyone who knows what the bucket path should be in this case

Thanks in advance