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Elastic Docs ›Painless Scripting Language [8.15] ›Painless contexts

Field context

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Field context

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Use a Painless script to create a script field to return a customized value for each document in the results of a query.

Variables

params (Map, read-only)
User-defined parameters passed in as part of the query.
doc (Map, read-only)
Contains the fields of the specified document where each field is a List of values.
params['_source'] (Map, read-only)
Contains extracted JSON in a Map and List structure for the fields existing in a stored document.

Return

Object
The customized value for each document.

API

Both the standard Painless API and Specialized Field API are available.

Example

To run this example, first follow the steps in context examples.

You can then use these two example scripts to compute custom information for each search hit and output it to two new fields.

The first script gets the doc value for the datetime field and calls the getDayOfWeekEnum function to determine the corresponding day of the week.

doc['datetime'].value.getDayOfWeekEnum().getDisplayName(TextStyle.FULL, Locale.ROOT)

The second script calculates the number of actors. Actors' names are stored as a keyword array in the actors field.

doc['actors'].size()

By default, doc values are not available for text fields. If actors was a text field, you could still calculate the number of actors by extracting values from _source with params['_source']['actors'].size().

The following request returns the calculated day of week and the number of actors that appear in each play:

GET seats/_search
{
  "size": 2,
  "query": {
    "match_all": {}
  },
  "script_fields": {
    "day-of-week": {
      "script": {
        "source": "doc['datetime'].value.getDayOfWeekEnum().getDisplayName(TextStyle.FULL, Locale.ENGLISH)"
      }
    },
    "number-of-actors": {
      "script": {
        "source": "doc['actors'].size()"
      }
    }
  }
}
{
  "took" : 68,
  "timed_out" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 11,
      "relation" : "eq"
    },
    "max_score" : 1.0,
    "hits" : [
      {
        "_index" : "seats",
        "_id" : "1",
        "_score" : 1.0,
        "fields" : {
          "day-of-week" : [
            "Thursday"
          ],
          "number-of-actors" : [
            4
          ]
        }
      },
      {
        "_index" : "seats",
        "_id" : "2",
        "_score" : 1.0,
        "fields" : {
          "day-of-week" : [
            "Thursday"
          ],
          "number-of-actors" : [
            1
          ]
        }
      }
    ]
  }
}
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