OpenSearch/docs/java-rest/high-level/document/exists.asciidoc

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[[java-rest-high-document-exists]]
=== Exists API
The exists API returns `true` if a document exists, and `false` otherwise.
[[java-rest-high-document-exists-request]]
==== Exists Request
It uses `GetRequest` just like the <<java-rest-high-document-get>>.
All of its <<java-rest-high-document-get-request-optional-arguments, optional arguments>>
are supported. Since `exists()` only returns `true` or `false`, we recommend
turning off fetching `_source` and any stored fields so the request is
slightly lighter:
["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/CRUDDocumentationIT.java[exists-request]
--------------------------------------------------
<1> Index
<2> Type
<3> Document id
<4> Disable fetching `_source`.
<5> Disable fetching stored fields.
[[java-rest-high-document-exists-sync]]
==== Synchronous Execution
["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/CRUDDocumentationIT.java[exists-execute]
--------------------------------------------------
[[java-rest-high-document-exists-async]]
==== Asynchronous Execution
The asynchronous execution of exists request requires both the `GetRequest`
instance and an `ActionListener` instance to be passed to the asynchronous
method:
["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/CRUDDocumentationIT.java[exists-execute-async]
--------------------------------------------------
<1> The `GetRequest` to execute and the `ActionListener` to use when
the execution completes.
The asynchronous method does not block and returns immediately. Once it is
completed the `ActionListener` is called back using the `onResponse` method
if the execution successfully completed or using the `onFailure` method if
it failed.
A typical listener for `GetResponse` looks like:
["source","java",subs="attributes,callouts,macros"]
--------------------------------------------------
include-tagged::{doc-tests}/CRUDDocumentationIT.java[exists-execute-listener]
--------------------------------------------------
<1> Called when the execution is successfully completed. The response is
provided as an argument.
<2> Called in case of failure. The raised exception is provided as an argument.