How to get inner hits field values in Nest or Elastic.Net library ? Alterantivly how to specify output type in Nest or Elastic.Net library?

Question

I am new to elasticsearch and I am having troubles with the Nest/Elastic.Net library. I would like to retrieve not the entire document but just part of it. I am able to do it in Postman but I cannot do it via Elastic.Net library or Nest library. Document structure looks like following

{
    “Doc_id”: “id_for_cross_refference_with_othersystem”
    “Ocr”:[
        {
            “word”: “example_word1”,
            “box”: [],
            “cord”: “some_number”,
},
{
            “word”: “example_word2”,
            “box”: [],
            “cord”: “some_number2”,
}

]
}

The document has a huge amount of properties but I am interested only in Doc_id , ocr.word, ocr.box and ocr.cord.

The following postman request fully satisfies my needs :

{
  "query": {
    "bool": {
      "must": [
        {
          "match": {
            "doc_id": "2a558865-7dc2-4e4d-ad02-3f683159984e"
          }
        },
        {
          "nested": {
            "path": "ocr",
            "query": {
              "match": {
                "ocr.word": "signing"
              }
            },
            "inner_hits": {
             "_source": {
                "includes":[
                  "ocr.word",
                  "ocr.box",
                  "ocr.conf"
                ]
             }
            }
          }
        }
      ]
    }
  },
  "_source":"false"
}

Result of that request is following :

{
    "took": 9,
    "timed_out": false,
    "_shards": {
        "total": 1,
        "successful": 1,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 3,
            "relation": "eq"
        },
        "max_score": 18.99095,
        "hits": [
            {
                "_index": "irrelevant",
                "_type": "irrelevant",
                "_id": "irrelevant",
                "_score": 18.99095,
                "_source": {},
                "inner_hits": {
                    "ocr": {
                        "hits": {
                            "total": {
                                "value": 1,
                                "relation": "eq"
                            },
                            "max_score": 7.9260864,
                            "hits": [
                                {
                                    "_index": "irrelevant",
                                    "_type": "irrelevant",
                                    "_id": "irrelevant",
                                    "_nested": {
                                        "field": "ocr",
                                        "offset": 11
                                    },
                                    "_score": 7.9260864,
                                    "_source": {
                                        "box": [
                                        ],
                                        "conf": "96.452858",
                                        "word": "signing"
                                    }
                                }
                            ]
                        }
                    }
                }
            },
            {
                "_index": "there_rest _of_object_is_ommited",
                
            },
            {
                "_index": "there_rest _of_object_is_ommited",
                
            }
        ]
    }
}

However when I try to convert that request to Nest Query DSL I am not able to achieve the same result. When I try to use the NEST library I don’t see any way to provide output result model/type. It looks like the Type of Document should match the output type which is not my case. Query that I am using :

var searchResponse = client2.Search<Model>(s => s
                                    .Query(q1 => q1.Bool(b1 => b1.Must(s1 =>
                                                                             s1.Match(m => m.Field(f => f.doc_id).Query("2a558865-7dc2-4e4d-ad02-3f683159984e")),
                                                                             s2 => s2.Nested(n => n.Path("ocr").Query(q2 => q2.Bool(b => b.Must(m => m.Match(m => m.Field(f => f.ocr.First().word).Query("signing")))))
                                                                            .InnerHits(ih => ih.Source(s => s.Includes(i => i.Field(f => f.ocr.First().word).Field(f => f.ocr.First().conf))))
                                                                                                                                                       )
                                                                            )))
                                                                                    .Source(false)
                                                                                );

Due to the fact that the Model type is created for a document and it doesn’t match the output type I am getting [null, null, null] as the output .

There is property such properties as Hits in ISearchResponse? But when I look into it I cannot see values of fields.

I tried using a low level client (Elastic.Net) and providing json request as a string. But It looks like there is not way of specifying the output type either. When I ran my code with the low level library it returns me 3 object of class Model with empty fields.

My questions are :

1. Is it possible to specify output type different from document type for Nest query DSL or Elatic.Net library ?

2. Is it possible to get values of the fields that I specified in request for inner hits with help of Nest or Elastic.Net libraries?

3. How would you solve such problem ? I mean we have huge documents and we don’t want to pass unnecessary information back and forth. The inner hits approach looks like a neat solution for us but it doesn’t look like it works with the recommended libraries Unless I am doing some silly mistake.

NOTE: I can achieve desired result with simple use of HTTPClient and manually doing what I need , but I hope to leverage library that is written for this purpose(Nest or Elastic.Net).