74 lines
2.2 KiB
Plaintext
74 lines
2.2 KiB
Plaintext
[[search-request-script-fields]]
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=== Script Fields
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Allows to return a <<modules-scripting,script
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evaluation>> (based on different fields) for each hit, for example:
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[source,js]
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--------------------------------------------------
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GET /_search
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{
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"query" : {
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"match_all": {}
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},
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"script_fields" : {
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"test1" : {
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"script" : {
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"lang": "painless",
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"source": "doc['my_field_name'].value * 2"
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}
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},
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"test2" : {
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"script" : {
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"lang": "painless",
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"source": "doc['my_field_name'].value * factor",
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"params" : {
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"factor" : 2.0
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}
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}
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}
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}
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}
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--------------------------------------------------
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// CONSOLE
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Script fields can work on fields that are not stored (`my_field_name` in
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the above case), and allow to return custom values to be returned (the
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evaluated value of the script).
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Script fields can also access the actual `_source` document and
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extract specific elements to be returned from it by using `params['_source']`.
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Here is an example:
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[source,js]
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--------------------------------------------------
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GET /_search
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{
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"query" : {
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"match_all": {}
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},
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"script_fields" : {
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"test1" : {
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"script" : "params['_source']['message']"
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}
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}
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}
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--------------------------------------------------
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// CONSOLE
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// TEST[setup:twitter]
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Note the `_source` keyword here to navigate the json-like model.
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It's important to understand the difference between
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`doc['my_field'].value` and `params['_source']['my_field']`. The first,
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using the doc keyword, will cause the terms for that field to be loaded to
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memory (cached), which will result in faster execution, but more memory
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consumption. Also, the `doc[...]` notation only allows for simple valued
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fields (you can't return a json object from it) and makes sense only for
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non-analyzed or single term based fields. However, using `doc` is
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still the recommended way to access values from the document, if at all
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possible, because `_source` must be loaded and parsed every time it's used.
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Using `_source` is very slow.
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