elasticsearch/docs/reference/scripting-languages/painless/painless-sort-context.md

mapped_pages
https://www.elastic.co/guide/en/elasticsearch/painless/current/painless-sort-context.html

Sort context [painless-sort-context]

Use a Painless script to sort the documents in 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 current document. For single-valued fields, the value can be accessed via doc['fieldname'].value. For multi-valued fields, this returns the first value; other values can be accessed via doc['fieldname'].get(index)

_score (double read-only)

The similarity score of the current document.

Return

double or String

The sort key. The return type depends on the value of the type parameter in the script sort config ("number" or "string").

API

The standard Painless API is available.

Example

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

To sort results by the length of the theatre field, submit the following query:

GET /_search
{
  "query": {
    "term": {
      "sold": "true"
    }
  },
  "sort": {
    "_script": {
      "type": "number",
      "script": {
        "lang": "painless",
        "source": "doc['theatre'].value.length() * params.factor",
        "params": {
          "factor": 1.1
        }
      },
      "order": "asc"
    }
  }
}