WARNING: Version 2.0 of Elasticsearch has passed its EOL date.
This documentation is no longer being maintained and may be removed. If you are running this version, we strongly advise you to upgrade. For the latest information, see the current release documentation.
Transform
editTransform
editDeprecated in 2.0.0.
The document can be transformed before it is indexed by registering a script in
the transform element of the mapping. The result of the transform is indexed
but the original source is stored in the _source field.
This was deprecated in 2.0.0 because it made debugging very difficult. As of now there really isn’t a feature to use in its place other than transforming the document in the client application.
Deprecated or no, here is an example:
{
"example" : {
"transform" : {
"script" : {
"inline": "if (ctx._source['title']?.startsWith('t')) ctx._source['suggest'] = ctx._source['content']",
"params" : {
"variable" : "not used but an example anyway"
},
"lang": "groovy"
}
},
"properties": {
"title": { "type": "string" },
"content": { "type": "string" },
"suggest": { "type": "string" }
}
}
}
Its also possible to specify multiple transforms:
{
"example" : {
"transform" : [
{"script": "ctx._source['suggest'] = ctx._source['content']"},
{"script": "ctx._source['foo'] = ctx._source['bar'];"}
]
}
}
Because the result isn’t stored in the source it can’t normally be fetched by source filtering. It can be highlighted if it is marked as stored.