69 lines
2.9 KiB
Plaintext
69 lines
2.9 KiB
Plaintext
[[transform-script]]
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=== Script Transform
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A <<transform, Transform>> that executes a script on the current payload in the
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watch execution context and replaces it with a newly generated one. The following
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snippet shows how a simple script transform can be defined on the watch level:
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TIP: The `script` transform is often useful when used in combination with the
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<<transform-search, `search`>> transform, where the script can extract only
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the significant data from a search result, and by that, keep the payload
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minimal. This can be achieved with the <<transform-chain, `chain`>>
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transform.
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[source,js]
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--------------------------------------------------
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{
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"transform" : {
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"script" : "return [ 'time' : ctx.trigger.scheduled_time ]" <1>
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}
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}
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--------------------------------------------------
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<1> A simple `painless` script that creates a new payload with a single `time`
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field holding the scheduled time.
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NOTE: The executed script may either return a valid model that is the equivalent
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of a Java(TM) Map or a JSON object (you will need to consult the
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documentation of the specific scripting language to find out what this
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construct is). Any other value that is returned will be assigned and
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accessible to/via the `_value` variable.
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The `script` attribute may hold a string value in which case it will be treated
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as an inline script and the default elasticsearch script languages will be assumed
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(as described in {ref}/modules-scripting.html#modules-scripting[here]). You can
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use the other scripting languages supported by Elasticsearch. For this, you need
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to set the `script` field to an object describing the script and its language.
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The following table lists the possible settings that can be configured:
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[[transform-script-settings]]
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.Script Transform Settings
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[options="header,footer"]
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|======
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| Name |Required | Default | Description
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| `inline` | yes* | - | When using an inline script, this field holds
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the script itself.
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| `file` | yes* | - | When referring to a script file, this field
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holds the name of the file.
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| `id` | yes* | - | When referring to a stored script, this
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field holds the id of the script.
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| `lang` | no | `painless` | The script language
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| `params` | no | - | Additional parameters/variables that are
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accessible by the script
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4+d| * When using the object notation, only one of `inline`, `file` or `id`
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fields must be defined
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|======
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When using the object notation of the script, one (and only one) of `inline`,
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`file` or `id` fields must be defined
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NOTE: In addition to the provided `params`, the scripts also have access to the
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<<watch-execution-context, Standard Watch Execution Context Parameters>>.
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