How can we eliminate the root structure for nested elements in the query result in Elasticsearch?

Elastic Stack Elasticsearch
1

How to write a query to eliminate nested elements "results" and "lines" from the below document.

{
  "_id": "0048160a463a73faaa6c90f5af027772",

  "_rev": "1-ff6255309f1b873a4e482310843a8a15",

  "timestamp": 1496275536932.6602,

  "results": {

    "lines": {

      "S1": [

        {

          "needed_key": "foo",

          "not_needed_key": 1

        }

      ],

      "S2": [

        {

          "needed_key": "bar",

          "not_needed_key": 1

        },

        {

          "needed_key": "foo_bar",

          "not_needed_key": 1

        }

      ],

      ...

    }

  },

  "station": "5002270",

  "another_not_needed_key": "something"

}

How can I write an elasticsearch query to get the output with out root structure from above document?

Below is my expected output.

{
 "_id": "fd298368a7a344b217698677f3f5a07d",
 "timestamp": 1496275536932.6602,
 "station": "5002270",
 "S1": {
     "needed_key": "foo",
     "not_needed_key": 1
    }
}

Thanks in advance..!

2

You can't rewrite a document in elasticsearch at search time.

But the question is may be why you did not index your document that way?

PUT /index/_doc/fd298368a7a344b217698677f3f5a07d
{
 "timestamp": 1496275536932.6602,
 "station": "5002270",
 "S1": {
     "needed_key": "foo",
     "not_needed_key": 1
    }
}
3

Thanks for the quick response @dadoonet

But my actual document consisting of 18 nested elements. So, which will be difficult to maintain each nested node in a separate index.

Thanks..!

4

Why would you not be able to store them in separate documents within the index? How frequently do you update these documents? Why would maintaining this be more difficult?

5

@Christian_Dahlqvist and @dadoonet : I need to write elasticsearch queries to fetch data from multiple nodes. So If I store multiple documents under single index would be problem for me to fetch the single search result from multiple documents.

6

Then it sounds to me like you will need to do some client-side post processing no matter which solution you go for.

7

Okay.! thanks @Christian_Dahlqvist

So we don't have any prompt solution to remove the root structure while we query for nested elements during search time from elasticsearch side ? please correct me if I am wrong.

8

No, as @dadoonet explained, you can not rewrite documents in Elasticsearch at search time.

9

@Christian_Dahlqvist : I don't want to rewrite the document in Elasticsearch, I Just wanted to restructure( like : removing the root structure, etc.. ) the elasticsearch results during search time

10

You can't.

11

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