62 lines
2.0 KiB
Plaintext
62 lines
2.0 KiB
Plaintext
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[[mapping-transform]]
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== Transform
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coming[1.3.0]
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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" : "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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"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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