[[painless-bucket-script-agg-context]] === Bucket script aggregation context Use a Painless script in an {ref}/search-aggregations-pipeline-bucket-script-aggregation.html[`bucket_script` pipeline aggregation] to calculate a value as a result in a bucket. ==== 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 numeric:: The calculated value as the result. ==== API The standard <<painless-api-reference, Painless API>> is available. ==== Example To run this example, first follow the steps in <<painless-context-examples, 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: [source,Painless] -------------------------------------------------- (params.max - params.min) + params.base_cost -------------------------------------------------- Note that the values are extracted from the `params` map. In context, the aggregation looks like this: [source,js] -------------------------------------------------- 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" } } } } } } } -------------------------------------------------- // CONSOLE // TEST[setup:seats] <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