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This change unifies the way scripts and templates are specified for all instances in the codebase. It builds on the Script class added previously and adds request building and parsing support as well as the ability to transfer script objects between nodes. It also adds a Template class which aims to provide the same functionality for template APIs Closes #11091
62 lines
2.0 KiB
Plaintext
62 lines
2.0 KiB
Plaintext
[[mapping-transform]]
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== Transform
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The document can be transformed before it is indexed by registering a
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script in the `transform` element of the mapping. The result of the
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transform is indexed but the original source is stored in the `_source`
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field. Example:
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[source,js]
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--------------------------------------------------
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{
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"example" : {
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"transform" : {
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"script" : {
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"inline": "if (ctx._source['title']?.startsWith('t')) ctx._source['suggest'] = ctx._source['content']",
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"params" : {
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"variable" : "not used but an example anyway"
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},
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"lang": "groovy"
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}
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},
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"properties": {
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"title": { "type": "string" },
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"content": { "type": "string" },
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"suggest": { "type": "string" }
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}
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}
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}
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--------------------------------------------------
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Its also possible to specify multiple transforms:
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[source,js]
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--------------------------------------------------
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{
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"example" : {
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"transform" : [
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{"script": "ctx._source['suggest'] = ctx._source['content']"}
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{"script": "ctx._source['foo'] = ctx._source['bar'];"}
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]
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}
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}
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--------------------------------------------------
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Because the result isn't stored in the source it can't normally be fetched by
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source filtering. It can be highlighted if it is marked as stored.
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=== Get Transformed
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The get endpoint will retransform the source if the `_source_transform`
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parameter is set. Example:
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[source,bash]
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--------------------------------------------------
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curl -XGET "http://localhost:9200/test/example/3?pretty&_source_transform"
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--------------------------------------------------
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The transform is performed before any source filtering but it is mostly
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designed to make it easy to see what was passed to the index for debugging.
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=== Immutable Transformation
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Once configured the transform script cannot be modified. This is not
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because that is technically impossible but instead because madness lies
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down that road.
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