Modifying response

Elastic Stack Elasticsearch
1

We have a need to modify the response document(s) from a query before returning it to the user.
For example, we might need to rename a document field to a more user-friendly name.

I understand that elasticsearch has extensions or other means of doing this. So if anyone can point me in the right direction, i would greatly appreciate it.

thanks

2

Painless Script is an option:

{
    "query" : {
        "match_all": {}
    },
    "script_fields" : {
        "alias_field" : {
            "script" : {
                "source": "doc['name.keyword'].value"
            }
        }
    }
}
3

Thank you for your reply. Much appreciate it.
I’m sorry but I must not be getting it, because when I read the docs in painless APIs it seems to work for values of fields VS actual field names...but the Painless APIs might be the right answer and I am not getting it.
Can you confirm how I can change the field name in a source doc, say from “random_field_name” to “friendly_field_name”

Thanks

4

This create a script field 'friendly_field_name' to replace field 'random_field_name' in source doc:

  {
        "query" : {
            "match_all": {}
        },
        "script_fields" : {
            "friendly_field_name" : {
                "script" : {
                    "source": "doc['random_field_name.keyword'].value"
                }
            }
        }
    }

And it returns like:

{
  "took": 3,
  "timed_out": false,
  "_shards": {
    "total": 5,
    "successful": 5,
    "skipped": 0,
    "failed": 0
  },
  "hits": {
    "total": 2,
    "max_score": 1,
    "hits": [
      {
        "_index": "test2",
        "_type": "doc",
        "_id": "2",
        "_score": 1,
        "fields": {
          "friendly_field_name": [
            "abc"
          ]
        }
      },
      {
        "_index": "test2",
        "_type": "doc",
        "_id": "1",
        "_score": 1,
        "fields": {
          "friendly_field_name": [
            "abc"
          ]
        }
      }
    ]
  }
}
5

As far as I know you can not change the source returned.

6

Thanks
if i am understand your, this script will be added to the _search endpoint and it will ADD new scripted field in the response, called "friendly_field_name" but the old field "random_field_name" will still be there too?

If that is true, is there a way just to rename the field with a script without adding a new field?

7

the old field "random_field_name" will still be there too?

The old field will not be in response.

is there a way just to rename the field with a script without adding a new field

The source can not be changed. The option I have learned is adding a new script field using Painless Script.

8

@wangqinghuan this is awesome. Thanks.
Where r u located? Are you interested in freelance work? We could use someone like you on our team.