I would like to avoid parent/child solution and I am wondering if in a single query/request I can return some documents.

I have documents “rate:

{ id="123", docType="rate", "grade":100}
{ id="456", docType="rate", "grade":0}
{ id="789", docType="rate", "grade":45}

I have documents “topics”:

{ id="abc", docType="topic", "title":"Alien"}
{ id="def", docType="topic", "title":"Suspiria"}
{ id="a12", docType="topic", "title":"Ring"}

All documents are in the same index.

_search Request (to improve) is:

    {
    "size": 0,
    "query": {
        "bool": {
            "must": [
                {
                    "term": {
                        "docType": {
                            "value": "rate"
                        }
                    }
                }
            ]
        }
    },
    "_source": false,
    "aggs": {
        "Topics": {
            "terms": {
                "field": "topicId",
                "size": 2
            },
            "aggs": {
                "Grades": {
                    "terms": {
                        "field": "grade"
                    }
                }
            }
        }
    }
}

Response is:

{
    "took": 9,
    "timed_out": false,
    "_shards": {
        "total": 1,
        "successful": 1,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 10000,
            "relation": "gte"
        },
        "max_score": null,
        "hits": []
    },
    "aggregations": {
        "Topics": {
            "doc_count_error_upper_bound": 0,
            "sum_other_doc_count": 25511,
            "buckets": [
                {
                    "key": "abc", <---------------------------------- here
                    "doc_count": 3,
                    "Grades": {
                        "doc_count_error_upper_bound": 0,
                        "sum_other_doc_count": 0,
                        "buckets": [
                            {
                                "key": 100,
                                "doc_count": 2
                            },
                            {
                                "key": 0,
                                "doc_count": 1
                            }
                        ]
                    }
                },
                {
                    "key": "def", <---------------------------------- here
                    "doc_count": 2,
                    "Grades": {
                        "doc_count_error_upper_bound": 0,
                        "sum_other_doc_count": 0,
                        "buckets": [
                            {
                                "key": 0,
                                "doc_count": 1
                            },
                            {
                                "key": 100,
                                "doc_count": 1
                            }
                        ]
                    }
                }
            ]
        }
    }
}

I am wondering if it is possible to have a query/request to get (via “script” or any other solution, or another query ^^) _source documents from the aggregations (“topic” documents) by the result key id returned (see “<——— here” above)

Excepted top hits returned documents _source response I would like:

.../...
    _source .../...: 
        { id="abc", docType="topic", "title":"Alien"}
        { id="def", docType="topic", "title":"Suspiria"}
.../...