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88 lines
2.4 KiB
Markdown
88 lines
2.4 KiB
Markdown
---
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mapped_pages:
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- https://www.elastic.co/guide/en/elasticsearch/painless/current/painless-bucket-script-agg-context.html
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products:
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- id: painless
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---
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# Bucket script aggregation context [painless-bucket-script-agg-context]
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Use a Painless script in an [`bucket_script` pipeline aggregation](/reference/aggregations/search-aggregations-pipeline-bucket-script-aggregation.md) to calculate a value as a result in a bucket.
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## Variables [_variables]
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`params` (`Map`, read-only)
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: User-defined parameters passed in as part of the query. The parameters include values defined as part of the `buckets_path`.
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## Return [_return]
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numeric
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: The calculated value as the result.
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## API [_api]
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The standard [Painless API](https://www.elastic.co/guide/en/elasticsearch/painless/current/painless-api-reference-shared.html) is available.
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## Example [_example]
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To run this example, first follow the steps in [context examples](/reference/scripting-languages/painless/painless-context-examples.md).
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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.
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This example takes the values from a min and max aggregation, calculates the difference, and adds the user-specified base_cost to the result:
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```painless
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(params.max - params.min) + params.base_cost
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```
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Note that the values are extracted from the `params` map. In context, the aggregation looks like this:
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```console
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GET /seats/_search
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{
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"size": 0,
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"aggs": {
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"theatres": {
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"terms": {
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"field": "theatre",
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"size": 10
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},
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"aggs": {
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"min_cost": {
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"min": {
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"field": "cost"
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}
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},
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"max_cost": {
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"max": {
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"field": "cost"
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}
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},
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"spread_plus_base": {
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"bucket_script": {
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"buckets_path": { <1>
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"min": "min_cost",
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"max": "max_cost"
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},
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"script": {
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"params": {
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"base_cost": 5 <2>
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},
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"source": "(params.max - params.min) + params.base_cost"
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}
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}
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}
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}
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}
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}
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}
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```
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1. The `buckets_path` points to two aggregations (`min_cost`, `max_cost`) and adds `min`/`max` variables to the `params` map
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2. The user-specified `base_cost` is also added to the script’s `params` map
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