[[painless-contexts]]
== Painless contexts

A Painless script is evaluated within a context. Each context has values that
are available as local variables, an allowlist that controls the available
classes, and the methods and fields within those classes (API), and
if and what type of value is returned.

A Painless script is typically executed within one of the contexts in the table
below. Note this is not necessarily a comprehensive list as custom plugins and
specialized code may define new ways to use a Painless script.

[options="header",cols="<1,<1,<1"]
|====
| Name                              | Painless Documentation
                                    | Elasticsearch Documentation
| Ingest processor                  | <<painless-ingest-processor-context, Painless Documentation>>
                                    | {ref}/script-processor.html[Elasticsearch Documentation]
| Update                            | <<painless-update-context, Painless Documentation>>
                                    | {ref}/docs-update.html[Elasticsearch Documentation]
| Update by query                   | <<painless-update-by-query-context, Painless Documentation>>
                                    | {ref}/docs-update-by-query.html[Elasticsearch Documentation]
| Reindex                           | <<painless-reindex-context, Painless Documentation>>
                                    | {ref}/docs-reindex.html[Elasticsearch Documentation]
| Sort                              | <<painless-sort-context, Painless Documentation>>
                                    | {ref}/sort-search-results.html[Elasticsearch Documentation]
| Similarity                        | <<painless-similarity-context, Painless Documentation>>
                                    | {ref}/index-modules-similarity.html[Elasticsearch Documentation]
| Weight                            | <<painless-weight-context, Painless Documentation>>
                                    | {ref}/index-modules-similarity.html[Elasticsearch Documentation]
| Score                             | <<painless-score-context, Painless Documentation>>
                                    | {ref}/query-dsl-function-score-query.html[Elasticsearch Documentation]
| Field                             | <<painless-field-context, Painless Documentation>>
                                    | {ref}/search-fields.html#script-fields[Elasticsearch Documentation]
| Filter                            | <<painless-filter-context, Painless Documentation>>
                                    | {ref}/query-dsl-script-query.html[Elasticsearch Documentation]
| Minimum should match              | <<painless-min-should-match-context, Painless Documentation>>
                                    | {ref}/query-dsl-terms-set-query.html[Elasticsearch Documentation]
| Metric aggregation initialization | <<painless-metric-agg-init-context, Painless Documentation>>
                                    | {ref}/search-aggregations-metrics-scripted-metric-aggregation.html[Elasticsearch Documentation]
| Metric aggregation map            | <<painless-metric-agg-map-context, Painless Documentation>>
                                    | {ref}/search-aggregations-metrics-scripted-metric-aggregation.html[Elasticsearch Documentation]
| Metric aggregation combine        | <<painless-metric-agg-combine-context, Painless Documentation>>
                                    | {ref}/search-aggregations-metrics-scripted-metric-aggregation.html[Elasticsearch Documentation]
| Metric aggregation reduce         | <<painless-metric-agg-reduce-context, Painless Documentation>>
                                    | {ref}/search-aggregations-metrics-scripted-metric-aggregation.html[Elasticsearch Documentation]
| Bucket script aggregation         | <<painless-bucket-script-agg-context, Painless Documentation>>
                                    | {ref}/search-aggregations-pipeline-bucket-script-aggregation.html[Elasticsearch Documentation]
| Bucket selector aggregation       | <<painless-bucket-selector-agg-context, Painless Documentation>>
                                    | {ref}/search-aggregations-pipeline-bucket-selector-aggregation.html[Elasticsearch Documentation]
| Watcher condition                 | <<painless-watcher-condition-context, Painless Documentation>>
                                    | {ref}/condition-script.html[Elasticsearch Documentation]
| Watcher transform                 | <<painless-watcher-transform-context, Painless Documentation>>
                                    | {ref}/transform-script.html[Elasticsearch Documentation]
|====

include::painless-contexts/index.asciidoc[]