44 lines
1.1 KiB
Plaintext
44 lines
1.1 KiB
Plaintext
[[mapping-field-names-field]]
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=== `_field_names` field
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The `_field_names` field indexes the names of every field in a document that
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contains any value other than `null`. This field is used by the
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<<query-dsl-exists-query,`exists`>> query to find documents that
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either have or don't have any non-+null+ value for a particular field.
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The value of the `_field_name` field is accessible in queries and scripts:
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[source,js]
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--------------------------
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# Example documents
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PUT my_index/my_type/1
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{
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"title": "This is a document"
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}
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PUT my_index/my_type/1
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{
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"title": "This is another document",
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"body": "This document has a body"
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}
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GET my_index/_search
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{
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"query": {
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"terms": {
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"_field_names": [ "title" ] <1>
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}
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},
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"script_fields": {
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"Field names": {
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"script": "doc['_field_names']" <2>
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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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<1> Querying on the `_field_names` field (also see the <<query-dsl-exists-query,`exists`>> query)
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<2> Accessing the `_field_names` field in scripts (inline scripts must be <<enable-dynamic-scripting,enabled>> for this example to work)
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