elasticsearch/docs/reference/scripting-languages/painless/painless-bucket-script-agg-context.md

mapped_pages	products
https://www.elastic.co/guide/en/elasticsearch/painless/current/painless-bucket-script-agg-context.html	id painless

Bucket script aggregation context [painless-bucket-script-agg-context]

Use a Painless script in an bucket_script pipeline aggregation to calculate a value as a result in a bucket.

Variables [_variables]

params (Map, read-only)

User-defined parameters passed in as part of the query. The parameters include values defined as part of the buckets_path.

Return [_return]

numeric

The calculated value as the result.

API [_api]

The standard Painless API is available.

Example [_example]

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

The painless context in a bucket_script aggregation provides a params map. This map contains both user-specified custom values, as well as the values from other aggregations specified in the buckets_path property.

This example takes the values from a min and max aggregation, calculates the difference, and adds the user-specified base_cost to the result:

(params.max - params.min) + params.base_cost

Note that the values are extracted from the params map. In context, the aggregation looks like this:

GET /seats/_search
{
  "size": 0,
  "aggs": {
    "theatres": {
      "terms": {
        "field": "theatre",
        "size": 10
      },
      "aggs": {
        "min_cost": {
          "min": {
            "field": "cost"
          }
        },
        "max_cost": {
          "max": {
            "field": "cost"
          }
        },
        "spread_plus_base": {
          "bucket_script": {
            "buckets_path": { <1>
              "min": "min_cost",
              "max": "max_cost"
            },
            "script": {
              "params": {
                "base_cost": 5 <2>
              },
              "source": "(params.max - params.min) + params.base_cost"
            }
          }
        }
      }
    }
  }
}

1. The buckets_path points to two aggregations (min_cost, max_cost) and adds min/max variables to the params map
2. The user-specified base_cost is also added to the script’s params map