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136 lines
No EOL
3.3 KiB
Text
---
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id: enElasticsearchPainlessPainlessFieldContext
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slug: /en/elasticsearch/painless/painless-field-context
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title: Field context
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description: Description to be written
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tags: []
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---
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<div id="painless-field-context"></div>
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Use a Painless script to create a
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[script field](((ref))/search-fields.html#script-fields) to return
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a customized value for each document in the results of a query.
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**Variables**
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`params` (`Map`, read-only)
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: User-defined parameters passed in as part of the query.
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`doc` (`Map`, read-only)
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: Contains the fields of the specified document where each field is a
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`List` of values.
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[`params['_source']`](((ref))/mapping-source-field.html) (`Map`, read-only)
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: Contains extracted JSON in a `Map` and `List` structure for the fields
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existing in a stored document.
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**Return**
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`Object`
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: The customized value for each document.
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**API**
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Both the standard <DocLink id="enElasticsearchPainlessPainlessApiReferenceShared">Painless API</DocLink> and
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<DocLink id="enElasticsearchPainlessPainlessApiReferenceField">Specialized Field API</DocLink> are available.
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**Example**
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To run this example, first follow the steps in
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<DocLink id="enElasticsearchPainlessPainlessContextExamples">context examples</DocLink>.
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You can then use these two example scripts to compute custom information
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for each search hit and output it to two new fields.
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The first script gets the doc value for the `datetime` field and calls
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the `getDayOfWeekEnum` function to determine the corresponding day of the week.
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```Painless
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doc['datetime'].value.getDayOfWeekEnum().getDisplayName(TextStyle.FULL, Locale.ROOT)
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```
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The second script calculates the number of actors. Actors' names are stored
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as a keyword array in the `actors` field.
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```Painless
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doc['actors'].size() [^1]
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```
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[^1]: By default, doc values are not available for `text` fields. If `actors` was
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a `text` field, you could still calculate the number of actors by extracting
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values from `_source` with `params['_source']['actors'].size()`.
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The following request returns the calculated day of week and the number of
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actors that appear in each play:
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```console
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GET seats/_search
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{
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"size": 2,
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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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"day-of-week": {
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"script": {
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"source": "doc['datetime'].value.getDayOfWeekEnum().getDisplayName(TextStyle.FULL, Locale.ROOT)"
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}
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},
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"number-of-actors": {
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"script": {
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"source": "doc['actors'].size()"
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}
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}
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}
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}
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```
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{/* TEST[setup:seats] */}
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```console-result
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{
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"took" : 68,
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"timed_out" : false,
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"_shards" : {
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"total" : 1,
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"successful" : 1,
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"skipped" : 0,
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"failed" : 0
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},
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"hits" : {
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"total" : {
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"value" : 11,
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"relation" : "eq"
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},
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"max_score" : 1.0,
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"hits" : [
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{
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"_index" : "seats",
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"_id" : "1",
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"_score" : 1.0,
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"fields" : {
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"day-of-week" : [
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"Thursday"
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],
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"number-of-actors" : [
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4
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]
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}
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},
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{
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"_index" : "seats",
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"_id" : "2",
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"_score" : 1.0,
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"fields" : {
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"day-of-week" : [
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"Thursday"
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],
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"number-of-actors" : [
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1
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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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```
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{/* TESTRESPONSE[s/"took" : 68/"took" : "$body.took"/] */} |