Exists API
editExists API
editThe exists API returns true
if a document exists, and false
otherwise.
Exists Request
editIt uses GetRequest
just like the Get API.
All of its 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:
Synchronous execution
editWhen executing a GetRequest
in the following manner, the client waits
for the 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 4xx
or 5xx
error code, the high-level
client tries to parse the response body error details instead and then throws
a generic ElasticsearchException
and adds the original ResponseException
as a
suppressed exception to it.
Asynchronous execution
editExecuting a 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
completed the ActionListener
is called back using the onResponse
method
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:
Source exists request
editA 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.