OpenSearch/docs/painless/painless-contexts/painless-update-by-query-co...

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[[painless-update-by-query-context]]
=== Update by query context
Use a Painless script in an
{ref}/docs-update-by-query.html[update by query] operation to add,
modify, or delete fields within each of a set of documents collected as the
result of query.
*Variables*
`params` (`Map`, read-only)::
User-defined parameters passed in as part of the query.
`ctx['_op']` (`String`)::
The name of the operation.
{ref}/mapping-routing-field.html[`ctx['_routing']`] (`String`, read-only)::
The value used to select a shard for document storage.
{ref}/mapping-index-field.html[`ctx['_index']`] (`String`, read-only)::
The name of the index.
{ref}/mapping-type-field.html[`ctx['_type']`] (`String`, read-only)::
The type of document within an index.
{ref}/mapping-id-field.html[`ctx['_id']`] (`int`, read-only)::
The unique document id.
`ctx['_version']` (`int`, read-only)::
The current version of the document.
{ref}/mapping-source-field.html[`ctx['_source']`] (`Map`)::
Contains extracted JSON in a `Map` and `List` structure for the fields
existing in a stored document.
*Side Effects*
`ctx['_op']`::
Use the default of `index` to update a document. Set to `none` to
specify no operation or `delete` to delete the current document from
the index.
{ref}/mapping-source-field.html[`ctx['_source']`]::
Modify the values in the `Map/List` structure to add, modify, or delete
the fields of a document.
*Return*
`void`::
No expected return value.
*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 following query finds all seats in a specific section that have not been
sold and lowers the price by 2:
[source,console]
--------------------------------------------------
POST /seats/_update_by_query
{
"query": {
"bool": {
"filter": [
{
"range": {
"row": {
"lte": 3
}
}
},
{
"match": {
"sold": false
}
}]
}
},
"script": {
"source": "ctx._source.cost -= params.discount",
"lang": "painless",
"params": {
"discount": 2
}
}
}
--------------------------------------------------
// TEST[setup:seats]