The exists API returns
true if a document exists, and
GetRequest just like the Get API.
All of its optional arguments
are supported. Since
exists() only returns
false, we recommend
turning off fetching
_source and any stored fields so the request is
When executing a
GetRequest in the following manner, the client waits
boolean to be returned before continuing with code execution:
boolean exists = client.exists(getRequest, RequestOptions.DEFAULT);
Synchronous calls may throw an
IOException in case of either failing to
parse the REST response in the high-level REST client, the request times out
or similar cases where there is no response coming back from the server.
In cases where the server returns a
5xx error code, the high-level
client tries to parse the response body error details instead and then throws
ElasticsearchException and adds the original
ResponseException as a
suppressed exception to it.
GetRequest can also be done in an asynchronous fashion so that
the client can return directly. Users need to specify how the response or
potential failures will be handled by passing the request and a listener to the
asynchronous exists method:
The asynchronous method does not block and returns immediately. Once it is
ActionListener is called back using the
if the execution successfully completed or using the
onFailure method if
it failed. Failure scenarios and expected exceptions are the same as in the
synchronous execution case.
A typical listener for
exists looks like:
A variant of the exists request is
existsSource method which has the additional check
that the document in question has stored the
source. If the mapping for the index has opted
to remove support for storing JSON source in documents then this method will return false
for documents in this index.